[coldtea]

>Each ongoing request eats machine resources and counts towards the browser request limit (6 or so).

And in most cases this doesn't matter at all.

[Mitranim]

Agreed, often it doesn't matter. Sometimes it DOES matter (high latency / low bandwidth / weak device), and then your program is slower than it could be. Why not pursue async primitives that let you manage resources properly at no downside?