This is why Sony starts strong and Microsoft still wins the race. Sony is still on a high from the ps4 plus a new console is going to sell like crazy is going to sell like crazy anyways for the first few months.
The issue isn't really how many games they sold in the past but how many gamers the zenimax purchase will pull over to xbox. Doom, elder scrolls, and fall out are still beloved franchises so folks will be hyped to hear news about them. For the growing headcount in their studios. Outside of Insomniac most of the Sony studios just released at most 2 games last gen and Santa Monica ,Bend, plus Media Molecule just released only 1. So we get what maybe 2 games per studio for this gen plus Covid happened. I would love it if Sony's first party studios expanded to the point they looked more like mini AAA third part publishers. I can't say I would be filled with hype for the new studio purchases unless it is Japanese. Blue point although nice would be a what took you so long to acquire this studio.
Let's see, last gen:
-Insomniac and Japan Studio released a lot of games last gen.
-Media Molecule last gen released Tearaway, Tearaway Unfolded, Dreams and did help with LBP Vita and LBP3 (plus Sackboy for PS5).
-Santa Monica released GoW 3 Remastered, GoW 2018, had to cancel a game that was into production, incubated several indie studios/games and this year is supposed to release GoWR.
-Bend released Uncharted Golden Abyss, Uncharted Fight for Fortune, Days Gone, is working on its PC port and pretty likely next year will release DG2.
-Guerrilla released Killzone Shadow Fall, Horizon, did help with Killzone Mercenary or Death Stranding, and this year releases HZD PC port and Horizon 2.
-Naughty Dog released TLOUR, Uncharted Collection, U4, Lost Legacy, TLOU2, did help on the Vita Uncharted games and hosts the ICE team and is supposed to work on TLOU2 MP which sounds may end being a separate game.
-Sucker Punch released Infamous Second Son, First Light and GoT.
-San Diego released 7 MLB games and did help Guns Up!, Kill Strain, Drawn to Death and StarBlood Arena.
-London released 4 titles and did help in other ones.
-They also have Polyphony (GTS) and Pixel Opus (new team, 2 PS4 games).
-Evolution released DC before shutting down.
In addition to this they released a ton of 2nd party games (Quantic Dream, From Software, Bluepoint, RAD, Supermassive, Housemarque and many other ones).
So what are you talking about? Sony has an insane output of 1st and 2n party output. And most of their studios reported to be growing and/or to have grown a lot in the recent years and Sony said they will acquire more studios. If MS has been buying a lot of studios recently is because Sony has and had a way bigger output of first (and second) party games so they want to catch up and to be more or less in the same level in the future. These recently purchased studios won't start releasing big next gen exclusive games until at least late 2022.
The think is, we know some of the studios purchased by MS will continue releasing games on PS after signed the deals, some of them with timed console exclusivity. So the impact of these exclusivities will be smaller than the already small impact we could expect considering their sales were a tiny portion of the over 1.5 Billion games (and counting) sold on PS4.
Sony has a super top notch 1st (and 2nd) party output in terms of amount of games, GOTY candidates and awards and sales. And since they are growing, they will have more in the future. Microsoft has a long road to make not to pass, but to match Sony's output.