Suffice to say that 50 points is considered a major edge, and it increases exponentially so 100 points is much more of an edge than 2x a 50 point edge. Here [2] is a rating expectation calculator. If Erdogmus and Carlsen played a best of 10 match, Carlsen would be expected to win 97% of the time, draw 2% of the time, and lose less than 1% of the time.
[1] - https://en.wikipedia.org/wiki/Ya%C4%9F%C4%B1z_Kaan_Erdo%C4%9...
[2] - https://wismuth.com/elo/calculator.html#rating1=2669&rating2...
He is currently the youngest GM.
Generally speaking it's expected that chess players will peak around their late 20s and slowly decline from there, with sharp declines around age 50. It's unusual but not unheard of for players in their 40s to win major tournaments. 42 year old Levon Aronian won several last year, but it was considered a notable example of longevity every time he won.
In terms of raw numbers, there are currently 30 players in their 30s, 15 players in their 40s, 4 players in their 50s, and no players older that in the top 100. The youngest is 14-year old Yagiz Kaan Erdogmus, who is considered the greatest chess prospect of all time.
In chess there’s a concept of strength, and ELO is used as a rough estimate of this. Further there are FIDE rankings like IM and GM that have certain requirements to achieve.
In most sports, there’s never such an age gap. Think of basketball or football. You don’t see 12 year olds hitting the equivalent of GM in those respective sports (going pro?) and being able to compete with the 35 year olds, do you? In most sports, they wouldn’t even be allowed to enter but in chess they could.
Is your point that young kids have an advantage in chess, making it harder to keep up as an adult? They clearly don't. No 12 year old has ever been able to seriously compete with top players, at best they can hold a few draws or win a blitz game here and there. As far as I'm aware Judit Polgar was the only 12 year old to even break into the top 100, and she's an outlier among outliers. Right now the top 3 players in the world are all in their 30s, and there's only one player in the top 50 who's younger than 18.
And they were right that "a lot of really strong players are 12 years old" doesn't by itself help clarify where they are relative to elite competition at other age bands let alone clarify what age band perform bests at the end of the day. Even now I still don't understand how "a lot of 12 year old are good" is to supposed to answer that even implicitly. If anything the natural reading of that would be an implication that they are among the most competitive, yet your elaboration says the opposite.
There's a lot more wrong with your comment that someone capable of making logical inferences can readily see, so I won't go into them.