What steam brought to the table was the first content delivery network for games. Digital Marketplaces were not a thing when Steam launched, and most software was still sold on store shelves. They are reliable, and customer friendly - that's why no other content delivery network has gotten any kind of foothold, because competitors consistently create platforms that are more difficult to navigate and screw customers over shortly after their launch by removing content or having some sort of major rights-issue.

Steam Workshop and Steam Community market account for almost nothing in the grand scheme of what makes Valve its money.

They have spent tons on developing the tools to play games on Linux through Proton, and have shown themselves to be enthusiasts themselves when it comes to supporting gamers with some of the more robust VR systems as well.