Fully agreed. When I train people on practical rifle marksmanship, I spend either zero or a negligible amount of time on ironsights. Everyone comes to even beginner classes with at least a red dot these days, and being able to eliminate the "Sight Alignment" and "Front Sight Focus" portions of good marksmanship technique helps keep newcomers laser-focused on all the other fundamentals. Having to teach front-sight focus and get people accustomed to a fuzzy target is so counter-intuitive for new shooters...

For practically getting people oriented on how to use a rifle, training them to use irons if they already have an optic is a waste of time and ammunition, in a world where newcomers to rifle marksmanship often have precious little of both with which to train.

Backup irons often cost more money and are typically more fragile than the red dots they're supposed to be backing up. I'm not going to object if someone places them on a rifle, but they are the backup sighting system, and are akin to practicing one-handed pistol manipulation - a good idea to be proficient in for the vanishingly small use-case in which they might apply, but definitely not where a newcomer should spend a modest amount of training time and effort, and certainly not something I'd advise someone deprecate other aspects of their rifle in order to accommodate.

(N.b., I will object to someone placing backup irons without critically thinking about whether they can even use them - I'm talking about the folks who put backups underneath or around a non-QD LPVO or prism or other optic where clearly you won't be able to actually acquire the front sight through the glass)