Anyone can already make its own testnet, which is called "signet". The problem is, how to make a testnet, where mining would be decentralized, and where anyone could mine new coins? Part of the solution is to send coins to Proof of Work puzzles, or similar scripts, like it is done in the current signet: And then, you have a lot of testnets, where users are splitted between many different networks. Which means, that if you want to test something, then you have some users here, some users there, and other users somewhere else, and it is harder to coordinate some things. Because for example, if each user has its own testnet, then you no longer can "hide in a crowd", because there is no "crowd", if you are the only user. Also, tests are then connected to a specific chain, so the same transactions are migrated over and over again, between different networks, so if one person tested "OP_CHECKSIG", then you cannot Ae888 Mc to some block explorer, but you have to repeat all tests yet again. Exactly. The problem is not about making any chain (because it is quite trivial, and that's how a lot of altcoins were made; also, regtest can be used, if some local network is needed), but to make something, which will be used by the community, to send worthless coins back and forth, and where anyone could mine something, make some transactions, and leave (without worrying about the future of such testnet, and resource consumption, if it could self-reset, and clean up that mess automatically, on a regular basis; while also allowing to keep some history for those, who will want to do that, and refer to past transactions or blocks).
Anyone can already make its own testnet, which is called "signet". The problem is, how to make a testnet, where mining would be decentralized, and where anyone could mine new coins? Part of the solution is to send coins to Proof of Work puzzles, or similar scripts, like it is done in the current signet: And then, you have a lot of testnets, where users are splitted between many different networks. Which means, that if you want to test something, then you have some users here, some users there, and other users somewhere else, and it is harder to coordinate some things. Because for example, if each user has its own testnet, then you no longer can "hide in a crowd", because there is no "crowd", if you are the only user. Also, tests are then connected to a specific chain, so the same transactions are migrated over and over again, between different networks, so if one person tested "OP_CHECKSIG", then you cannot Ae888 Mc to some block explorer, but you have to repeat all tests yet again. Exactly. The problem is not about making any chain (because it is quite trivial, and that's how a lot of altcoins were made; also, regtest can be used, if some local network is needed), but to make something, which will be used by the community, to send worthless coins back and forth, and where anyone could mine something, make some transactions, and leave (without worrying about the future of such testnet, and resource consumption, if it could self-reset, and clean up that mess automatically, on a regular basis; while also allowing to keep some history for those, who will want to do that, and refer to past transactions or blocks).

Anyone can already make its own testnet, which is called "signet". The problem is, how to make a testnet, where mining would be decentralized, and where anyone could mine new coins? Part of the solution is to send coins to Proof of Work puzzles, or similar scripts, like it is done in the current signet: And then, you have a lot of testnets, where users are splitted between many different networks. Which means, that if you want to test something, then you have some users here, some users there, and other users somewhere else, and it is harder to coordinate some things. Because for example, if each user has its own testnet, then you no longer can "hide in a crowd", because there is no "crowd", if you are the only user. Also, tests are then connected to a specific chain, so the same transactions are migrated over and over again, between different networks, so if one person tested "OP_CHECKSIG", then you cannot Ae888 Mc to some block explorer, but you have to repeat all tests yet again. Exactly. The problem is not about making any chain (because it is quite trivial, and that's how a lot of altcoins were made; also, regtest can be used, if some local network is needed), but to make something, which will be used by the community, to send worthless coins back and forth, and where anyone could mine something, make some transactions, and leave (without worrying about the future of such testnet, and resource consumption, if it could self-reset, and clean up that mess automatically, on a regular basis; while also allowing to keep some history for those, who will want to do that, and refer to past transactions or blocks).

Anyone can already make its own testnet, which is called "signet". The problem is, how to make a testnet, where mining would be decentralized, and where anyone could mine new coins? Part of the solution is to send coins to Proof of Work puzzles, or similar scripts, like it is done in the current signet: And then, you have a lot of testnets, where users are splitted between many different networks. Which means, that if you want to test something, then you have some users here, some users there, and other users somewhere else, and it is harder to coordinate some things. Because for example, if each user has its own testnet, then you no longer can "hide in a crowd", because there is no "crowd", if you are the only user. Also, tests are then connected to a specific chain, so the same transactions are migrated over and over again, between different networks, so if one person tested "OP_CHECKSIG", then you cannot Ae888 Mc to some block explorer, but you have to repeat all tests yet again. Exactly. The problem is not about making any chain (because it is quite trivial, and that's how a lot of altcoins were made; also, regtest can be used, if some local network is needed), but to make something, which will be used by the community, to send worthless coins back and forth, and where anyone could mine something, make some transactions, and leave (without worrying about the future of such testnet, and resource consumption, if it could self-reset, and clean up that mess automatically, on a regular basis; while also allowing to keep some history for those, who will want to do that, and refer to past transactions or blocks).