The fact that you haven't encountered something is not evidence
that it is impossible, or false. It just means you haven't seen it.
You're correct, but you also can't prove a negative. What I can say, and prove, is that I've personally seen over a couple hundred guns used by people that I know do regular dry practice. Based on how I do dry practice, I can safely say that those people I know do at least as much as I do. But, if they only did 10% of what I do, it still represents well over 1,000,000 dry presses on handguns. This is no longer a small population statistically speaking.
Out of all that use, not one of those guns has ever broken due to dry practice.
I had an extractor break in my 1911. That was probably due to practicing type 3 malfunctions with snap caps; not caused by dry practice.
I hear of firing pins or strikers breaking and some claim it's due to dry practice, but there's no evidence. It's more likely that the failure is due to improperly hardened metal than too many dry presses. Of the few firing pins I've actually examined, they look more like the result of compression fractures than tension failure.
A long time ago, the hardening process was not as controlled as it is today. A single action hammer that was allowed to slam into the frame, without the slight cushioning the primer provided, could crack the frame. This single type of event has been brought forward and is used to claim that dry practice causes all manner of breakage. I'm sure the same thing could happen in a modern gun, like a 1911, if the trigger is pressed with the slide off; don't do that.
I reiterate, dry practice will not damage your gun. Until I see some proof that it will, I will continue to do and teach to do dry practice. It is the single best way to improve your shooting.