I have heard that early classes from bootcamps tend to have great people, while the later classes are both more "dillute" in terms of raw talent and more starved of instruction time (as the bootcamp pinches pennies to make a profit).
I have worked with bootcamp grads who are amazing engineers and ones who are terrible, same with ivy league CS grads.
I do think there was a bit of a gold rush with fly-by-night programs popping up everywhere; as a result the quality bar for bootcamp grads has probably shifted down on average, but I expect there are still some very talented trying to jumpstart a new career this way.
Early movers in the space like DevBootcamp and App Academy were able to be quite selective about who they took, often picking primarily non-CS grads from elite universities looking to redeploy high levels of baseline intelligence and communication skills into a more lucrative field than whatever they studied at university. That was definitely my motivation once I realized I might never afford a middle-class lifestyle (e.g. homeownership, children) if I kept going in the scientific field I trained for.
I have worked with bootcamp grads who are amazing engineers and ones who are terrible, same with ivy league CS grads.