My apologies for bad phrasing and conveying an attitude that was far from my original intent.
Of course I do not consider women to be some impersonal 'material' like oil, gas, or gold, ready to be 'exploited'. Unfortunately many guys out there *do* have this extremely competitive and misogynistic attitude. So becoming acquaintances with them won't bring you anywhere.
And of course people participate in activities for the 'sheer joy of learning/personal development'. It is just that some activities are a lot more prone to attract 'PUAs trying to meet women' (and to a much lesser extent women trying to meet guys). So all I was trying to say is there is little causal relationship between 'meeting new guys through social events' and 'meeting new women'. Voilà

"even if the Spanish class you’re attending is one giant sausage party, these are still potential new friends, and new friends have other friends they can introduce you to"

Ah yes...the friends introducing you to friends introducing you to friends a.k.a the 'exponential social network expansion' myth. SO. NOT. HAPPENING.
I think the vast majority of guys participating at all kinds of 'social activities' (language classes, meetups, latin dances etc etc etc) do so for the sole purpose of meeting women, because they have trouble meeting them otherwise.
Which means, that even if these guys become your 'friends' they will never and I mean ne-he-ver introduce you to any new girls. Why would they do that when, in their world, single attractive women are such a scarce resource? Why would they increase their own competition?
So yeah, I really do not think one should count on the 'expanding social network' factor, except maybe on extremely rare cases of befriending a guy who is literally swimming in female acquaintances (someone in the fashion industry maybe, or a male nurse?) who will also think of you as such an 'awesome bro' that he will open the 'floodgates' just for you. Unfortunately such guys are heavily sought after and they won't hang out with 'just about anyone'. Heck I remember watching a Woody Allen interview from the mid-1970s where he was joking that even his dentist was doing his darndest to become his friend in the hopes of being introduced to 'hot chicks' working in the movie industry.