MS bought a complete publisher with the intent to lock out the competition and secure the software exclusively for themselves and their platforms and services. How is timed exclusivity any different? Especially since they usually don't exclude the PC. It's actually less bad since Xbox owners will eventually see the game, yet they were ecstatic when Bethesda got acquired. Which one is it?
Microsoft didn't buy Bethesda just so Sony fans couldn't play their new games. It's incredibly absurd and biased to think otherwise. They bought them because
1. They were looking to sell, and another company buying them might not be good for Microsoft
2. They add significant value to Xbox
3. They add significant value to Game Pass
4. It helps their current studios by being able to collaborate with Bethesda
5. It helps Bethesda games benefit from collaboration with Xbox's other game studios
6. It includes some super popular IP like Elder Scrolls, Fallout, Doom, and Wolfenstein
7. They now own Bethesda's tech like their very popular id tech engine
Also, Bethesda being owned by Microsoft increase their job security, and allows many of their studios to not be shut down, like sure BGS was never going to be in danger, but what about Arkane or Tango? Would you rather one of those studios die off for the sake of being able to play a few more games on Playstation? Acquisitions substantially help the developers and the games themselves, timed exclusives are a drop in the bucket to developers and the games are unlikely to be improved because of the small cash infusion. The only people who think timed exclusives and acquisitions are the same are people who dislike Xbox or are fearmongering about consolidation. I'm not saying Xbox/PS/Nintendo should all buy every single developer, but the ones they do buy are almost always going to be much better off than had they not been bought.
I would be SHOCKED if excluding Playstation owners was even in the top 10 reasons for Microsoft to buy Bethesda. Timed exclusives only purpose is to exclude gamers, that's the difference between the two strategies, Insomniac is in a much better place now that they're owned by Sony, and their games will benefit, this isn't about Xbox vs Playstation, you don't have to defend a bad strategy (for gamers) just because Sony is doing it, I sure didn't think it was a good strategy when Xbox abused it during the 360 gen. In general I'd rather have devs stay independent, but if the choice is between being acquired or having to sell out for constant timed exclusivity I'd rather they get acquired (by anybody, MS/Nintendo/Sony) because it generally allows for better, more polished, or more creative games