What these unrelated services did doesn't refute the point that a small team can put together a blogging service. Most components you need even already exist as pre-packaged FOSS. On top of it, one company on your list had a complex product that was built by a hand-full of college students in its early days. The Instagram company they bought also had just 13 employees.

Twitter is another horribly overstaffed example. The Ev Williams signature touch.

for the first two, they are dealing with tons of data on people's interests, machine learning, spam algorithms, search infrastructure, not just the pageviews.

the only hard technical part of Medium is perhaps their content recommendations, but thats it. dealing with a ton of pageviews is hard, yes but nowhere near the complexity of dealing with what others are doing. you can solve that problem with more machines and money if need be. hard problems (ie google search) can only be solved with PHDs and thinking.

> Because it’s not straightforward, and it’ not that many people? Facebook has 100x that number. Twitter has 25x. Airbnb hired almost 10x that number in 2015 alone. Stripe has almost 4x that number.

While true, this doesn't really answer the GP's question, does it?