[fezzez]

Not the original poster but I think the best answer to that would be from a talk DHH (the guy who made rails) gave about language choice.

He pointed out out that when he started his company there was no rails, or any great support for writing a server in ruby. He pointed out that it's actually surprisingly simple to get a barebones version of whatever library you like done in your preferred language. The original working version of rails was less than 2000 lines of code. Sure, there are no bells and whistles, but that's how rails started, and look where it is right now.

Compared to the ruby ecosystem in 2004, the Ocaml ecosystem actually pretty full of great libraries. Yeah, it's still tiny in comparison to the big server languages, but it's more than enough to build reliable systems on top of.