Idk.... I feel like its easier to relate to someone of your own age group.
For example someone who is in their late teens early 20s could not relate to a person in their 40s when they bring up their kids growing up and going off to college or like house mortgages, or divorces and stuff. And I feel like an older person would have no interest in a lot of things younger people might like now a days (like cringy fandoms and tv shows or the latest "interesting" music, or how easy it is to make such dumb decisions just because etc.)
Age does matter to some degree especially if you are looking for close friends to talk to daily about your everyday life. I always feel like once I tell someone my age and they share their's (and usually this only happens if they are way older, and not a pervy dude) they tend to not want to talk anymore or they start taking on this parental role over me which is just...eerh. Nothing wrong with it but I already have two overbearing parents as it is and I don't really want a third 😂.
But that's just me personally. I find I have a hard time relating to people even in their late 20s because to be quite frank, I'm in my beginning years of adulthood. Whereas they had at least 10 years of it and have already experienced the "hard" level of life and I'm technically still on the tutorial.
Besides I feel like for older people they wouldn't want to hang around others that lack their level of maturity.
But again this is just for me personally and I know other people in SL view it differently and probably don't even share their age so they don't have to worry about it.