I don't think this is significantly true.
I made friends through those clubs, though, and never dated anyone from there.
I'd strongly disagree with this. They seem to be organising and doing things constantly, in my experience (married 40s male).
Generally as a result of being active and sociable, you become a person people want to be around. You can't give off a 'desperate to meet girls' vibe, so focusing on too many details can work against you.
I met my wife volunteering for a charity. Heavy bias of female to male in the volunteer group. Regular meetings to keeping seeing the same group and getting to know each other.
My cousin who is an underemployed balding middle aged divorcee (at times living with his mother - cue George from Seinfeld) met his current long term girlfriend on a skiing trip.
Granted this was somewhere in the Alps. Also my cousin is awesome at smalltalk and unrealistic business ideas.
they are all paired up
I tried skiing through which i met tons of people but very few single women. Tried bjj, no women at all. Hiking and camping groups, again no single women. I still do all of these activities but very few women. I've actually never met a woman ,single or otherwise, mountain biking, which is my main goto in summer.
Truth is that women don't generally do a lots of activities.