Have you actually used steam lately? They did something to it on Mac that made it reset to the store page every time it loses focus and gains it back. Including when you try to read the code in your mail to be able to login, or when entering 3d secure codes for a purchase.
Basically you can't use it without another device to check your mail/texts.
I use Steam regularly, I don’t game on a Mac regularly. To be fair I don’t think most people use Macs for gaming. It’s been that way for as long as I can remember. Apple has a tight grip on mobile gaming though, that’s a money maker for them.
I don't play many mobile games but I tested The Battle of Polytopia when it was in beta and I still play it today. So it's not a complete loss. Android has solid emulation scene though.