Not to defend Musk but, as a matter of fact, he has written his fair share of code so he probably knows what he's talking about in this case.

I just refreshed twitter's home page and for me it made 111 http requests (per Chrome's dev tools). That includes static resources like images and style sheets. So only ~10% are made from the browser and the other 90% must be due to microservice architecture on the backend, I suppose?