Instagram is still pretty lean from what I’ve heard.
Pre-revenue that is possible. Post revenue, you'd need at least lawyers and accountants in each country you operate in. Then you need systems to respond to subpeonas and legal requests, that is a hundred people right there.
IG was 13 employees when you had a fraction of the images and they didnt have to be profitable, rather just grow by burning $. Now consider scale and profitability and you need even more people to grow tech cost consciously.
This seems intuitively false. Adding more people to tech domains can actually decrease effectiveness with more expense, resulting in lower profits. Obviously, there is a sweet spot, but Twitter is a basic product regardless of how many countries it operates within.
Suppose you are Twitter and operating in, say, {Ghana, Russia, Korea, Mexico, and Pakistan}. You're served with subpoenas and legal IP requests in each country. If you dont respond in time, your license to operate may be revoked. Each request is in the native language. How do you "scale" this technically? Can one lawyer handle these across the world? How?
Furthermore, developing tech for managing this is likely to be unnecessary as there are existing software packages already out there. Doing business across the world and handling legal issues is not unique to Twitter.
I generally agree with your response, but note that you've just converted FTEs to contractors/outsourcers and "reduced" FTEs that way. You'd have to do the same with accountants and many other country-level positions. But w2-->1099 isnt really a "win".