alt Hacker NewsNot using bleeding edge web "standards" is also hardly comparable to the office of having a physical presence in every locale though. Software developers seem to be uniquely good ad overvaluing small convenience gains for themselves compared to the pain inflicted by breaking compatibility multiplied by the set of affected users.
Most websites are glorified rich text or forms. And most of the rest should be that. This is even more true for the kinds of websites people need to use rather than some designers art experiments. They don't actually need all these fancy features except to make their developer's work slightly easier.
A lot of the time it's not software developers who define it and it's about the budget. Usually it's the product decision. E.g. an agency who has constant recurring experience with it might indicate that supporting N% browsers costs this much with cost increasing the higher the percentage. E.g. you want to use CSS flex you might get 97% to 99% of all World users, because there's going to be certain percentage for which it won't work. If you claim to support those old browsers you will need to test with them too and be able to easily spin up etc It's not just knowledge of what you can or can't use, it will be extra permutations of testing everything.