I've also wondered about it.

I think the answer is, "you don't really need 10,000 engineers". You can do a lot with small teams of engineers. This was true before AI. Macintosh was designed and built from scratch with a team of 3 which eventually peaked at 20-30. Does anyone seriously believe a company building a web app needs 10,000 engineers?

There's a lot more to the world than web apps. What if you need to build a 6th-generation fighter? Can a team of 30 do that with some AI agents?

"web app" covers a lot of surface though. Yes, if the web app in question is a static site that AI can shit out in 20 minutes, it doesn't need 10,000 engineers, but what about building, and running, and operating something like, say, Instagram. Which has a web app. End-to-end, all of it, down to racking servers in data centers across the world, 10,000 engineers sounds reasonable. So start by defining what this hypothetical webapp and how much kubernetes is involved.