It might be useful if age correlated to fitness or energy levels but that frequently isn't the case.

Chronological age doesn't indicate how athletic or agile people are. I once shared a sleeping compartment on a train with an 80-year-old who climbed up to the top bunk without even using the ladder. Lots of people in their 70s and even 80s can walk for miles.
In some cases it might be useful to know how big somebody is. People often ask whether they should get first-class tickets for trains. The first class seats are a bit bigger which might be an advantage for someone who is much taller or fatter than average, but second-class seats are quite big enough for the majority of travellers.

I agree with Geoff that age isn't necessarily related to fitness. I have two female friends who are both in their mid sixties. One dashes around like a fit 20 year old and the other one walks slowly with her head down like a frail 80 year old.

I appreciate Joannyc's reasons for the post but no, I don't want my birth year on my profile. It's not information that I readily give out.

I absolutely agree with you that it borders on criminal that posters who simply don't have the agility or energy of other people not only issue-forth travel dictums totally shaped to their limitations, they issue it with sarcasm, bullying mockery, preen as "well-seasoned" travel experts, insist that some OP's plans are undoable, a "mistake" -- and insist this is the only travel "wisdom" not just their idiosyncratic take on the world of travel.

Perhaps you were jesting about attaching a birthyear to the profile, but the problem I see with that is that some posters cautioning against this or that beautiful location or convenient highway or an exciting multi-country trip aren't in their 70s. They're in the fifties! There are some posters on this board over 60 for whom age hasn't meant American retiree vacationing. They still enjoy a road trip or train travel, head up to the top of hilltowns, seeing more than one country, staying up late at night in cities, actually getting up at dawn and follow a map in Venice all day seeing great artworks all day long, and getting up and doing it the next too.

So I think posting ages or birthdates would be misleading. I think that mental progress from no longer sharing one's personal travel tips to creating a European travel dogma or becoming a tour guide-mommy or daddy herding other people into taking your favorite vacation over and over and over is a personality thing, not an age thing. They can't wait for the young'uns and newbies to innocently show up on Fodor's so they can clear their throats and repeat themselves.

And then there are the people who simply enjoy lecturing others.