Just compare Instagram written in Python to Google Wave, Google+ or any other Google's social media, written in C++/Java :))))

> Instagram has one billion monthly users generating $7 billion a year.

Doesn't Instagram serve mostly static content that's put together in an appealing way by mobile apps? I'd figure Instagram's CDN has far more impact than whatever Python code it's running somewhere in it's entrails.

Cargo cult approaches to tech stacks don't define quality.

The point is that it's still one project. You need to count the failures as well to rule out survivorship bias.

And you can put 7 billion of effort into tweaking your python application performance?