The way I see it, Sony's acquisitions add to the industry. None of their acquisitions have taken any games off of Xbox.
On the other hand, Xbox's acquisitions have mainly been about taking games off of PlayStation. That's their way of leveling the playing field. That's not productive or gamer-friendly.
Sony acquisitions were either in the PS1/ PS2 era, where it was before the era of massive 100+ teams studios, or the ones that the got more recently, like Insomniac games. Most of Sony early acquisitions were net positives as they were already working for Playstation only. It allowed them to get funding and expand in size to answer the marked demands more easily. Without Sony some of those studios would/could have died in the PS2>PS3 transition. Only studios like Bungie are already so big that they can probably go public if they wanted to, are in my opinion not a net positive for all gamers as there is a risk of Sony limiting their output and twisting them to their own interest( like demanding a VR game even if the studio did not want to) Small studios fundamentaly needed a publisher anyway so they are under that publisher control in a sense. Xbox was in control when it was time to make Scalebound and for us end users there is little difference between a deal between a publisher and a studio, outside of the possibility of that studio to change course in the future.There is no productivity in acquisition.
Just like how Xbox acquisiion takes games from other systems, Sony is denying talent studios from making multiplatform games in the future, in order to boost their talent.
At end of the day, its about keeping talent people to yourself. Money talks, and us consumers get the end of the stick.
It is a fact that Xbox took Bethesda games from Sony. It is a fact too that Sony did the same with all the studios they had commandited games from. The difference is that Sony managed to do so when the studios were small and irrelevant compared to their status as a publisher and console maker. And they had worked hard to give them all the tools and cooperation to push those studios to allow them to go highter than they would alone. Xbox on the other hand refused and/or was unable to do the same. Imagine if Xbox got Bioware, maintained good relations with Bungie, Epic and Crytec ? They would have been better positioned now with maybe a few great games that we never got because they didn't try enough. And asking for studios to make games for you is not a problem, it is what is asked of console makers. Give us great experiences. Buying them is the next step. I do not see the problem, unless you are talking of EA who killed a lot of studios over the years.