You are just conflating random laws to a situation that doesn't apply; you think nobody can make something exclusive? Buy something and make the goods exclusive to a platform? Find me one ruling where the EU indicated that when it wasn't based on a monopoly. That section is about things like price fixing, actions involving multiple companies acting together to limit markets. Buying Bethesda doesn't limit anyone's ability to sell products... that's not in any way related to this. Companies can do things including buying companies to their advantage.. that's called capitalism.
I didn't say all anti-trust laws only apply to monopolies.. we are talking about a specific scenario.. a purchase/merger.
Here's the section of TEFU that applies to what I'm talking about:
Antitrust and Cartels Overview
ec.europa.eu
Dominating a market is not illegal.. and MS will not be dominating any markets after buying Bethesda.