I think this is more of a system question and less of an XP question.
If the system doesn’t make each point of a skill matter that much, then it will very much be a generalization gambit. I have a custom homebrew system that generally incentivizes spreading out points early on so that you can live long enough to specialize. Though the diminishing returns is high, each point of growth, in this system, is so significant that a person with 2 points in something will very often lose to someone with 3 points in it. And since lots of strategy appears in both social and combat situations to navigate you toward which skills you’ll be using in those rolls, the person who plans and implements well, can lean on their specializations more often.
I generally think that most of the classless systems generate more generalized characters because you don’t know what ‘situation’ you’ll be in on a MU*. In TableTop I’ve never been in a game where anyone was a generalist like we see online, even to hundreds of karma later type situations, or multi-year long campaigns.
On MUs, it’s system choice that will do this for you, keeping XP limited so you can’t just buy everything, and maybe having steps that matter when you achieve certain progression levels. These would all be very system dependent, so no one answer fits each situation.