Earlier quoted context omitted.
How did you not realize that one can run/evaluate code without actually broadcasting it? All you need is access to a node (plenty of public ones) and you can "simulate" any transaction(code) you would like.
Testing a dapp off the mainnet is like ensuring your website works on localhost. It will find some issues, but it's not representative of how it will look in deployment. In any case, for actual usage it should surprise nobody why everyone conflates Ethereum with money. No, your L2 chain does not qualify as an official solution.
It's absolutely representive of how it looks in deployment. You can test transactions EXACTLY how they would happen on mainnet.
I don't get your second point.