"after all those zillions spent they're still not the market leader nor the main platform with most hardware/software sales"
Most gamers don't care how much money a corporation makes or who is the market leader. The win here for gamers is Activision Blizzard games in game pass.
MS doesn't even seem focused on the FTC, they're basically just going through the checklist to appease the EU and CMA. They probably know they can win against the FTC easily in court - just like everyone else does.
Activision will be part of Microsoft this year. Sony had better take a COD deal while one is still on the table.
Those are indeed arguments, but that is not what regulators look for. Regulators look to see if it will harm competition and if consumers will get a worse deal.
They don't care about whether Sony believes you should grow vs buy studios.