It can be done but it's very expensive if you want platform evolution too. Browser makers do a lot of regression testing against real websites, they hardcode s

It can be done but it's very expensive if you want platform evolution too. Browser makers do a lot of regression testing against real websites, they hardcode site specific hacks and things like that, but most platform vendors aren't willing to do this. They'd rather do cost shifting onto developers. Finding developers who are willing to support the mistakes of the past forever is pretty hard, most will at some point try to deprecate stuff and bully devs by scaring their users with warnings and errors in some way, or pulling apps from app stores. Smart versioning strategies can help but it's ultimately a cultural and business model issue.