I've seen irons fail- though it's generally less catastrophic than electronic optics failing. I've had inserts fall out of front sights and rear sight drift. I've seen adjust rears get bent out of wack aswell. I've seen alot of those skinny fiber optics fall out of competition sights aswell.
Here was a night fision front where the insert fell out- still functional.
Here's a trijicon front sight that took a hard impact and then drifted.
Far Less functional cause POI changed during shooting- Though not enough to miss at close ranges.
Not all electronic optics are created equal- the same goes for iron sights. I like to see set screws/adhesives being used for fixed sights rather than just friction fit dovetails personally and obviously i dont like plastic.
But I can attest to mud being easier to blow out of a rear sight notch then the emitter holes on a rds. There's ways around that, better tech that can be applied for certain situations/holsters etc.
I've seen alot of people complain about plastic sights on glocks... I always liked plastic sights cause I figured that's the first thing you swapped on a handgun anyways- I didn't want to pay for good sights that I wasn't planning on using anyways- I never thought people would actually depend on plastic glock sights seriously though obviously they've been used in deadly shootings plenty effectively. Just cause something can fail doesn't mean that it will, and just cause something shouldnt fail doesn't mean it can't.
Here's a nasty plastic rear from a cz- it worked fine for a few years- but eventually just wore out and wouldn't hold zero.
The fella who owns it still uses it on a gun he keeps in his daily driver and that picture was taken in 2017... 🤦‍♂️
What I think is that the engineering that goes into iron sights is becoming an afterthought because the market is trending towards red dots on everything. People aren't interested in making iron sights bombproof because people don't plan on using them. Not all iron sight designs are created equal- and that's something rarely considered by folks who are selecting a new gun to carry because the general notion is that iron sights
cant fail- which isn't true.
Ymmv.