This is something I've noticed. /fit/ is about fitness in general but it's 90% lifting dominated. Same goes for /r/fitness on reddit.
Do lifters just use forums/boards more than other fitness enthusiasts?
Because these boards are just called fitness and the average Joe who imagines 'fitness' thinks of ripped dudes. The only way to get ripped is to train with weights, so the boards are dominated by lifting. People who run go to running forums, swimmers on swimming forums, etc. However, even those people can benefit from weight training too.
I don't really know about your question, but I do have a belief that sorta parallels yours. I think more people are into lifting then running, and the reason is because cardio is harder to do then lifting.
On the few occasions I have the opportunity to do so, I find it's a cool way to see parts of the neigborhood I haven't been around. Sometimes I'll take a short bus ride down the street and start there to vary the scenery. It's actually sort of nice.
winter is lifting only tho