I’ve commented before on how I’m worried about Steam being used as a vector for malware. Game publishers can push updates. Less-than-savory companies can buy ownership of titles from game publishers, possibly when they go out of business, which includes the right to push updates to user computers. Games run under Steam do not run in an isolated environment, and run with full access to a user’s account.

On Linux, I understand that it’s possible to run all of Steam in a (nonstandard) flatpak, which I suppose is probably the best option today for some users, though I don’t know what compatibility issues may be associated with that.