Yep, exactly.

I went down this "trades are great!" rabbit hole a while ago because I had a cousin who had a friend telling him: "You can be making 6 figures in 5 years as an electrician!" I was surprised when I found out his buddy didn't have a bridge to sell him as well.

Your career is not just about money earned. It is about the lifestyle. It is about your physical health over a long period of time. It is about your chance for advancement. It is about what you are going to be doing day-to-day.

yeah because the average dev guy can run marathons, right?

Working as a dev doesn't inherently prevent one from being healthy and active enough to be able to run a marathon, just gotta spend some time being active in your spare time. But killed knees and back due to a job in trades certainly will prevent you from running a marathon, no matter what you do with your free time.

Sitting in a chair all day is horrible for people though. (To say nothing of what it does for your attitude and personality).

You can easily mitigate that by making adjustments to your workplace (adjustable sitting/standing desk), as well as by avoiding spending a lot of time in a chair and being active outside of work. With trades, you cannot really do anything outside of work to successfully mitigate the damage done to your body, unfortunately.

A lot of what I've seen is that people in the trades will encourage their kids to go for the desk jobs because the trades are hard on your body and dangerous to boot.

It always seemed like the cargo culting around trade school doesn't come from it as a career option but rather because it comes from a bias against traditional colleges. In reality what we should be doing is making both the trades and college free so that students have their choice of career and education rather than trying to pigeonhole them down one path because education has transformed from a societal good to one purely for work.