The question itself seems strange to me, because one does not start miniature wargaming in a vacuum. Most people start, I think, buy finding other wargamers, which means most people will start by playing whatever it is that group plays, and then branch out later.
I've no doubt there are people who decide on a system first and THEN go looking for people in their area who play that (good luck if it's not something massive like WH), or who bootstrap a new group out of likeminded friends, but I think those are both outlier scenarios.
I can see the latter being the norm back in the per-internet days, but not today. Today I think what most people would do first is go looking for local groups to join via social media, and would only form new ones if/when the ones they found/tried weren't quite what they wanted and they knew others who might join them.
The former seems very "cart before the horse" and failure-prone to me.