You need to provide some real evidence for a claim like that, I think. Most of the world's military members run irons and are perfectly capable of succeeding with them. Red dots and other similar optics systems have been known to fail in adverse conditions; something that an iron sight will never do.
Telescopes will obviously be superior to either of the above but are for a different purpose than iron sights and as such aren't really comparable in such a discussion, in my opinion.
Are you f**king serious?! I guess the fact that Canada, the US, Britain, Germany, France, Denmark, Austria, Australia, New Zealand, Italy, Ireland, Norway, Netherlands, To name a few are all dumb for issuing optics to every infantry soldier. I'm sure they enjoy spending billions on optics that offer no advantages over iron sights..
In addition to the nations above who issue optics as standard equipment, there are countless other nations who's rifles are capable of mounting optics. Have a look around and tell me how many service rifles of current aren't manufactured with a flattop(that's an M1913 picatinny rail if you weren't sure) for mounting optics? How many SOF units aren't running optics of some sort?? Can you tell me if the trend in hunting rifles is in favor of iron sights or optics??? I'll give you a hint, it's definitely not in favor of irons. On the civilian side do you see more optics or irons being used in competition? Oh and I'm aware of the iron sight only divisions which are separated from the optics users for good reason...
The fact that iron sights have a nearly 100% failure rate when used in low or no light conditions means that iron sights are a "half a day" sighting system. The fact that iron sights require your eye to focus independently on three different objects at three different focal planes means they're very slow, especially when used on moving targets(you end up focusing on one only as your eye cannot focus on more than one at a time). The fact that iron sights require very consistent head position to be effective means they are very slow. Iron sights require you to mount the rifle to be used.
A quality reddot sight for example is very robust and works in all lighting conditions. The reddot also works with sub optimal head position or body position as in not having to mount the rifle to be used. A reddot offers both eyes open visual acuity and single focal plane focus. A superimposed dot appears on the target which is where BOTH of your eyes are focused. This makes placing rounds very easy and very fast. Tracking a moving target and superimposing the reddot is intuitive with both eyes open and the single focal plane concept.
Magnified optics of either the fixed or variable power design also offer many of the same advantages. Magnification offers a more precise aiming point(aim small miss small) and also greatly aids in positive target ID something that irons don't do. Optics offer the single focal plane advantage like a reddot. On lower magnification levels two eyes open is easily achieved. In fact with ACOG optics they require the user to keep both eyes open to take advantage of the Bindon Aiming Concept. Trijicon just manufacturered their 1,000,000th ACOG in November of 2017. the ACOG line is the most fielded military optic ever...But I'm sure it's just a gimmick as iron sights are just as good as optics.. Oh and Aimpoint has been selling their reddot sights to militaries for over 20 years, again just a gimmick.
the Son Tay raiders used Singelpoint(later known as Armson) OEG(occluded Eye Gunsight) optics to achieve 40 kills without losing a single member. This was done at night by the way, and the optic was selected as it offered serious advantages over iron sights... Have a read below.
http://soldiersystems.net/2015/11/19/sof-carbines-comparing-the-son-tay-gau-5aa-and-the-m4a1-cqbr-part-i/
Your statement about optics failing is a possibility. There is also the possibility of irons failing or the rifle itself. Use quality products and the issue isn't one. Optics also work well with eye issues, a reddot is much easier to see than irons. For those with astigmatism there are magnified and non magnified options that work with astigmatism. Irons only work with good eyes and daylight.
perhaps a few hours watching some informational videos and reading some articles might bring you up to speed on the advantages of optics over irons. Start with Aimpoint's youtube channel below.
https://www.youtube.com/user/AimpointChannel
Here's some guy demonstrating the difference between a reddot and irons.
https://www.youtube.com/watch?v=uZkQO6KdM4U
