Pure speculation: of the people who don’t like Epic, maybe 25% are legitimate, principled objections to their business practices. The rest are split evenly between people who just want to manage their entire library on a single platform, and folks just going along for the hate-ride because it seems like the “safe” position to take.
From a technical stance, Steam and GOG are superior platforms (for different reasons). For equal-price purchases, I can’t think of a single reason to choose Epic over other options. But claiming a game for free? That doesn’t make anyone a bad person.