The major information that you can take away from this whole case, is just how much Call of Duty means to Sony, and gaming in general. Some stats came out that there were a good number of people who only play Call of Duty. I mean they own a PS5 and the only game they own and play is Call of Duty. For Sony, it's a potential loss of a significant portion of their customer base.

Because they weren't the ones that got to buy Activision and Bethesda. If they were the games would still have been exclusives, just for Playstation instead of Xbox.

Every single gaming IP Sony has purchased pales in comparison to the sheer financial juggernaut that is COD. Purchasing Activision is bigger than all of Microsoft's other gaming purchases combined. There's a good chance it's bigger than all of the gaming purchases from Sony and Microsoft pre-Activision — combined.

As a gaming entity, Activision is in the same ballpark in size as Sony. Sony's market cap last I checked was ~$120b, but they also have a consumer electronics division, music division, movie division, image sensors division, etc. Without an acquisition markup Activision might be worth ~$50b today or so, and Sony's gaming-only value might be in the $60-80b range if I had to guess.

Activision-Blizzard has about 17,000 employees. Naughty Dog has 400.

Past acquisitions — by anyone — in the gaming market are completely and utterly incomparable to this acquisition.

Why is Sony against this

Because Sony don't want MS being more competitive, and owning ABK will do that.