Single-threaded + async-everything is a unique and powerful feature of Javascript. You might not like it every time, but it's useful most of the time. Most other languages make it easy to write single-threaded but blocking code where you need to reach for an extra solution to write async code, and not everyone needs to even use the same solution, and it doesn't necessarily work with the default blocking ecosystem.
We take that for granted in Javascript.
Once again, this is a very tired thread. Sometimes you just have to admit there are trade-offs and that you aren't going to have a taste for every decision on every trade-off every time. And that's okay.
Nobody in this thread is even interacting with TFA.
I agree with above comments that you could have taken any language. But you have a point, making async mandatory is a powerful thing.
This could have been done to any language tho, Java, TCL, Scheme, whatever.
IMO Tcl would have been a vastly preferable choice for a browser scripting language. Text is its native data type, and would have minimized impedance mismatches with other functional areas of the text-based HTML/HTTP environment. Also it would have been far easier for newbies to get started with web script hacking. At the time JavaScript seemed like alien algebra to a lot of non-computer science majors.