Sorry but that statement is crap. I'm sure if Twitter could be done by one person, they could. These companies have a LOT more going on than just banging out code.

I think the whole huge employee numbers are just a way for those big companies to justify to their investors their high valuations. "Oh yeah we have 700 employees, so we are a huge company, so 500 mil in VC funding is really not a lot for a huge company like us"

There seems to be an almost pathological bias against profitability with a lot of startups.

So I heard that some think that is because for a long while the R/D effort was outsourced to other companies, away from larger ones. I dunno if that is the case but in the company I worked for got acquired and did some pretty serious R/D. It could have been profitable but acquisition was obviously the easier way out so the investors took it.

I'm sure something like Twitter is useful but only to a large company, perhaps? I dunno.

That's not really it, if we're going to speak in generalizations it would be more fitting to talk about the investors that favor high risk/high reward growth patterns.

A site like Facebook would be impossible with just 10-15 people. Designing, implementing, and managing something on that scale is an insane amount of work. It probably takes a dozen ops/monitoring people just to keep the thing running.

Only with standard corporate solutions.

a Website (httpd etc) + Web Application server (CMS/CMF) + Application Container (J2EE and all that) + RDBMS (Oracle, MySQL...)

And multiply that to development, QA, and production environments.

Yes, that way you need millions just in licenses and hosting to run even a lol-site and hundreds of employees to keep the beast working.