When you talk about Valve as a business you're really talking about two different businesses that work closely together.
There is the Valve that makes a good game every 3-5 years. This company has a track record of good to great games, a track record where you don't have to wonder if you're going to get shafted as a customer. The games are good, get great support, and are always multiplayer and/or the foundation for a multiplayer mod community. Those three things are the best anti-piracy measures there are.
Then there is the Valve that built, maintains, and expands Steam, the premier digital distribution platform for PC games. Steam was a clunky piece of shit when it came out, but unlike every previous attempt at DD Valve kept improving it, making it run better, making it more convenient, adding features, etc. Contrast it with Origin, which will probably remain in beta forever only to get scrapped in a few years when EA corporate decides it "isn't working out", not realizing it isn't working out because they're not supporting/enhancing it enough for it to be a valid competitor.
There seems to be a good synergy between the two endeavors. Steam gives Valve a huge and varied "focus group" to test out new approaches with. They can throw something up against the wall and see if it sticks before putting major effort into it. Steam on the other hand benefits from Valve's track record with gamers which gets them to install it and leave it running even before they want a game they can only get from Steam.