The obliterator example is basically as good as it can get to compare the edition.
All that changed was -1T and a few points more. For a seemingly so strong unit (you still can get T5 and now have a bigger variety of weapons) isnt it strange that they completely disappeared?
Like a very few people using them? When the Iron Warriors were OP for lifting the 0-1 restriction... now there is no more 0-1 restriction. There is not even an actual FOC restriction as you can just pick multiples.
If that made them utterly broken and they did not change... why are they suddenly not broken now? No restriction at all. Come on! Fear the mighty obliterator!
Oh right... editions changed. Armies moved on. We are not in ****ing 3rd edition anymore.

You know what actually was broken and really needed a fix? Leash. That power would be devastating even today.

Wanna know whats fun? Space Marines just got leash. And I bet you wont see any Space Marine having a problem with that. However they will still complain about how OP it was when CSM had it while pointing out that their new PSI powers are fine.