And/or "shortage of programmers ticking all the boxes on this highly specific technology stack we're using". I get the impression that the greatest advantage of these development bootcamps from a hiring perspective is having a turnaround time short enough that they can focus narrowly on whatever technologies are trendy at the moment, as opposed to a traditional CS degree which is much more theory-centric and often a couple years out of date in its practical offerings.

It seems to me they already tend to offer quite high salaries.
Further increasing them could increase the number of available programmers, although there are going to be both short-term and long-term availability limits. And obviously, companies can't afford to pay arbitrary high salaries.

More specifically, I suppose that much of this labor demand comes from startups, which often operate on the brink of financial viability.
Startups have high failure rates, but a few of them generate a very high return on investment, which is what makes the whole startup industry viable: VCs are as risk averse as anybody else, but by diversifying their investments in many startups they reduce the variance of their return and thus obtain a positive expected utility. However, if failure rate goes up (for instance due to increased labor costs) without the other parameters changing, it would kill the whole industry, and I would expect this to occur in a very non-linear fashion, essentially as a threshold effect.