Aren't environment variables kind of a bad thing in Windows? They're global so installing an application that twiddles with them could break another application

Aren't environment variables kind of a bad thing in Windows? They're global so installing an application that twiddles with them could break another application. Isn't that what we had the registry for and now AppData? Path is a bit different because it's helpful being global so any command prompt can use it. Though the start menu search bar doesn't seem to so wouldn't it be better moved to a setting in the command prompt and Powershell applications themselves?