Given that this was the scientific consensus, "the competence of scientists that they make that mistake" compared to whom? Laymen? I'd still bet on the scientists.

If there's a real concern is not about "the competence of scientists that they make that mistake", but about the certainty of our grasp of the scientific facts in general.

It's not that those scientists were incompetent.

It's more like "science in general doesn't know as much as solidly as we'd like to think" about the matter.

Calling it a "mistake" vs just a lack of knowledge is a weird way of framing it. There was much discussion of "junk DNA" (now referred to as non-coding DNA) for years/decades - everyone realized it was an anomaly to be explained, but no-one knew the explanation. This comprises the vast majority (98%) of DNA - so clearly it was there for some reason.

Worry more about the financial incentives built into every nook and cranny of our economic system to the point it permeates scientific funding, that make it an asymmetric bet to say anything even if it is proven wrong later, than to spend a lot and say in the present, "I got nothing". Modern science is more an industrial complex where errors and overstatements are often the rational outcome of perverse economic incentives. More commonly known as publication bias or the file drawer problem.