The real problem is that the requirements for a social platform are getting very onerous, to the point that it takes at least several engineers working full time on the problem.

That really hurts a startup's ability to initially launch in the market, especially one with less VC money. (Certain BigCo new products can be thought of as a startup too, with limited budgets.)

This doesn't just affect social media companies, it affects almost any product where a user can upload data, or any product with a social feature, no matter how peripheral the feature is.

Turns out that's a wide swathe of technology, and that social features are fairly valuable.

Of course the big companies will eventually get around to launching in Europe anyway, it will just trail behind the rest of the world.