This was Microsoft’s strategy way-back-when. You can go surprisingly far, especially in enterprise, by covering all the basics without excelling at anything in particular, and fixing your mistakes.
Avoiding fatal flaws is really really important and is extremely difficult to do, so just managing to be mediocre at everything necessary is actually quite uncommon in my experience.
I have seen this particularly in my limited experience of founders and startups: you may need to be great at one thing, but you also need to be OK at many many things, and you must avoid the infinite sea of fatal flaws.
Slow compared to what? Amazon's website feels more responsive and more usable than 90% of online stores I've seen that carry orders of magnitude less variety of inventory. It loads fast, searches fast, provides for easy navigation between related products, and displays all needed information on one page without jank. Sure, it doesn't look modern, but it feels far more functional than the competition.
I suspect their search, classification, filters etc are all so broken because it's all based on a Google-style textual search, with no backend database driving those site features.
> where so much of revenue comes from the relatively few customers who are very deep in their usage.
I'm disputing that for retail.
I mean, just look at the Amazon retail operation - everyone agrees that the website is tired, ugly, and slow, but lots of people still do all their shopping from there because they're used to it and it's easier than maintaining accounts with 15 different retailers with 15 different websites. Amazon's bottom line seems to indicate that breadth-first algorithms work well on problems involving human populations.