If by interoperability you mean 'PCs Macs and Linux boxes can all play Java edition', then that's still there.

Mojang made the original version (now called Java edition).

Mojang then made Pocket Edition for iOS, and made it as a separate thing with no cross-play.

Mojang then got someone else to make the Xbox edition, again it didn't cross play with anything else.

Then Mojang sold to Microsoft.

Microsoft then made the iOS, Android, XBox, Nintendo Switch and Windows 10 editions all work together and have the same features and upgrade path.

So its not really fair to say that MS trashed the interoperability aspect - it was Mojang that started down the path of different versions for mobile/consoles. MS actually did a huge amount of work to make all those platforms work together again.

But yes there are now two seperate Minecrafts - Java edition, and all the others (previously known as Bedrock).

Its better than it was though, in interoperability terms.