It's surprising that it works for Zappos, which is just an online shoe store. Yes, there are people who are fanatical about shoes, but the business of selling and shipping them is not that exciting.
Is Valve's latest "new" IP DOTA2 successful when compared to the other set of MOBAs that have come out over the past few years?
Have Valve's forays into VR and hardware been successful compared to other companies in the space? e.g. the Vive, Oculus?
Looking at Steam itself, has the service dramatically improved since launch? Certainly there have been a lot of good incremental updates, e.g. two-factor auth. But the Apple App Store has seen a lot more updates in terms of search, discoverability, etc.
I am not an expert, and may have my details wrong about Valve. But I don't think the company has been especially successful outside of being the only game in town for buying AAA video games online.
It's probably best for Valve that Steam did happen, but if it's due to Valve's flatness, I would attribute that to the org's inability to resist Gabe rather than any sort of bonus wisdom that arose from that flatness.
Dota 2 I would estimate is #2 behind League of Legends, and it's too early to tell whether VR is working out, but guess which platform VR games are going to be delivered through?
(Besides Steam, their games are pretty successful: Half Life, Team Fortress, Portal, Counter Strike, Left 4 Dead)
This may not be your main point, but have you ever used the Steam store? It's the only app store that I've ever encountered that actually gives me valuable suggestions, and thus the only one into which I've sunk a considerable amount of money. (At least 200€, probably more. In second place is Google Play, where I spent some 7 € or so on apps.)
Just look at the huge percentage of games that are only purchased and never played (or even downloaded) to see that Valve has absolutely nailed the Steam store.
Regarding the actual argument: I agree that for a company this large, the turnout in form of actual products (esp. games) from Valve is surprisingly low. But I'm not sure if that's even a bad thing: For some studios, it works well to release 10 mediocre games within a certain amount of time. For other studios, it works better to release only one extraordinary game in the same timespan.
...but there's no one to do good customer service and other boring but necessary things.
Honestly, I don't know what Valve does any more, or if they have to do anything. They can just all take a year-long vacation, schedule some sales, and let people make them money by buying hats, games, or gun skins.