The OS can provide bug-for-bug compatibility with itself. To do so is clearly possible given the evidence that Windows does it.
To what extent that compatibility is required or desired is a different matter.
In any case, "Linux" has, for many years now, been commonly found with EXT3 as its default filesystem. This filesystem did not exhibit data-loss for the scenario in question. EXT4 does. How is this not a regression? We're not talking about a program crashing or running slowly or anything like that, we're talking about data loss. DATA LOSS. If there's one thing a computer should get right, it's storing the darn data and not losing it.