For starters, Steam updates about 4-5 times faster as the native client does.
I'm always playing my Steam account before the other accounts are 1/10th of the way updated.
Second, the Steam client works on Linux as well. Was setting up VR on Ubuntu last night as a matter of fact.
This. Steam being called bloatware and rubbish in year 2017 is ironicly humorous, but that is another discussion altogether.
Like said above, sometimes with my slow internet, it is nice to have all my games up to date so when I want to play something, it is ready to go instead of having to wait and loose interest or that time window, and Steam Auto Updates are extremely fast and efficient vs a dedicated launcher for a specific game that has to update once you launch and has no auto update function.
Second, people like the Steam social features, invite friends, track playtime, etc. It's not major to me personally, but it can be to some.
Why does this option keep getting ticked off automatically anyway and why/when was this implemented? I just don't see the reason for why this was changed in the first place.