That changed because they have a major refactor starting from Windows 7. They have it up to the spec and not so much more ad-hoc behavior this time.

To me it seems like cutting the compatibility arm is worth the price of having to keep a shitty, inconsistent behavior.

Apple has nailed it so well (don't make it backward compatible) for the last decade afterall, since Apple realized one the internet is so much better and source code management (and repository, backup, disaster recovery) became more accessible so that the cost of port became much lower.