Is not the same, Peanuts is a non serial gag news paper comic, Popeye is a non serial cartoon. They are non serial so it doesn't matter if they not age. The same can be said for the simpsons that only in few occasions they have shown a continuity. The pokemon anime in the other hand is a serial with a myth arc heavy in continuity, every arc leads to another and it has been acknowledge and referenced that previous story arcs did happen, maybe if they said this is totally the first time Ash starts his journey making a new continuity, but nope, somehow Ash has participated in 5 leagues, each of one during at least 6 months and he is still 10, I mean come on at least make him 12 or 13. If we go by the series way of thinking all previous episodes happened in less than a year with enough room that is not his birthday yet, because you know he started his journey when he was 10

The difference is Pokemon has an actual continuity to it, whereas the other shows mentioned don't.