I think that’s part of the argument. It isn’t just for Steam keys, it’s for alternate storefronts like GOG, Ubi, EA, Epic, etc. If you want to sell on Steam, you have to keep it the same price as anywhere else. It seems a bit harsh, but I am tentatively siding with Steam on this one. I’ve never had a company be as consumer friendly as Valve has been over their lifetime, and they’ve earned some brand loyalty. It’ll quickly dissolve if they start fucking people over, but for now, as far as I’m concerned, they get the benefit of the doubt.
You could very well be right, I haven’t read the full suit or done a lot of research on it, so I’m just going off the scraps I’ve read. I did check out isthereanydeal to look at price differences between Steam and Epic on some major titles, and all of them had even pricing. I don’t have a huge sample size, so if you want to look for some that have different prices, I’d be interested to see how much difference there is, and if, say, the lowest price on Epic has had a Steam sale after it where the game was priced higher on Steam.