As someone who seldom plays with friends (I have very few who want to play online), I just pick the store where the games are the cheapest or there’s a sale or something. It doesn’t really affect me that much.
But if all your friends are on steam, then check before getting a game on Epic, sometimes they don’t let you play together. Most of the time they do, though.
You’re not wrong. But voting with your wallet has a much bigger effect, I’d say.