I do recall being a younger person and lugging around the latest, hottest Think Brick I could get my hands on but at the time nothing was "light" so there was no concept of "heavy".
I don't think its so much an age thing so much as the fact that high power and light weight now come in the same package.
Edit: Today its possible to be out on the town all day, meetings etc with a mere iPad and a keyboard. If I need to do some heavy lifting I'll bring the M1 Air - but remember having to lug around those gigantic charging bricks because machines ate watts and batteries sucked? I'll never miss that. So Lenovo shaved 1/4th a lb off the laptop but the charging brick got 1/2 lb heavier.
And if so, at what age do older devs start doing this?
I walk to and from a parking space or bus stop to get to my office and lately I have been overpacking my backpack again. Maybe it is a mistake but I justify it in that soldiers train by carrying a heavy backpack. I sure am careful about getting on and off a bus.
For years i thought I had trouble with my shoulders but I found out it was TMD, a bite guard made a huge difference.
I recently started carrying a full size keyboard and mouse, because I find it harder and harder to adapt to the laptop keyboard and touchpad for extended periods of time.
The weight never bothers me; but again, it's a properly-designed laptop backpack. If I used a (cough) "professional-looking" briefcase or shoulder bag, it would really hurt to carry.
If you really need to look professional, I suggest finding a very small computer that can fit in the pocket of a trenchcoat. Keep in mind that today's computers are very fast, so they might be "good enough" to run Visual Studio / XCode / whatever on a moderately-sized project.
If the few pounds of a 16” MacBook Pro are causing you pain, even if you are over fifty, you should concern yourself more with taking better care of your body.
But, carrying a heavy lap top in a backpack for long periods of time is not a good idea. A few years of this in my 40s led to shoulder tendonitis that still has me seeing a physio regularly. I carry it in a hand held brief case now.
These North Face and Samsonite back packs designed for lap tops don't have the same supports that proper hiking backpacks have. You end up carrying all the weight on your shoulders instead of on your hips. Not a good idea!
I prefer larger screens so that I can increase font sizes and strain my eyes less. I also worry much more about ergonomics, because lots of laptop hacking has started to turn into RSI.
And that all means bigger laptops are better, and they are usually not lighter. I used a netbook in college - I can’t fathom it now.
Also you can never be too thin or too rich. Older devs can afford the sleeker laptops. And we don't need to do hard grunt work, so having a lightweight 'supervisor-top' is a mark of that. Look at briefcase dimensions, the C-suite always have the smallest/thinnest, if any at all.
Seems like you were born yesterday.
Also downgraded my camera kits, and often dont bring them places anymore.
That's why the LG Gram 17inch 2020 is the best laptop I've owned.
The screen is big enough to simulate two monitors and it is feather light.