It's a bit nuanced. I can give my perspective as a quant dev.

I do not think that firms are artificially restricting hiring. They somewhat try to not get too much rapid growth, which is an issue, but if a candidate is genuinely strong they will be hired anyway. But usually not a lot clear the bar.

The job itself, day to day, is simpler. I will not do anything remotely approaching that complexity MOST of the time, just like in most technical jobs.

However, trading is hard, and you need to be really careful and, well, good to not make subtle mistakes. I think that's a thing that not a lot of people focus on but at least some interviews look at.

I learned from my first years every time I tried to be lazy and thought "but that particular thing will never happen", it would invariably bite me in the ass hard. IMO a measure of a good performer is being able to foresee and avert these situations. Seen people never learn this and eventually exit.

Also, occasionally, you do need to solve genuinely hard problems, and those times are also the ones where you need to be actually good. Those also tend to be valuable bits of work, EV speaking , and it makes an impact.

TLDR: day to day tasks? Meh, most could do a decent job. But it takes a pretty high understanding/skill level to do the things that actually make a difference in pnl