I think we have different ideas of what “cheaply” means. To me freedom from surveillance and manipulation is kinda priceless - recognising that is impossible to completely avoid these things if you want to be online, but also recognising there are degrees, and FB tops the charts for worst offender by a country mile.
I guess it does depend where you draw the line of what’s acceptable and what isn’t and how much you value those things over “cheap” advertising*. And I’d still disagree with you about choices of platforms if this is actually what you advocate - you’d get a lot more action on Slack, and other newer platforms, than FB - it’s depressing people still buy into the kool-aid sold long ago that FB is actually necessary/the best for that kind of thing (hint: it isn’t anymore, you got played).
A lot of the kids (you know, the ones really necessary as lifeblood of a political movement, especially one that should appeal to youth) reject FB almost completely now except as required by family obligations; they’re on Instagram, Snapchat, Slack, Discord, and they’ll try out anything new to see if it’s got stuff to offer them. Insta you’ll still get a lot of FB brand surveillance, but not as much the others. But yeah, there’s opportunities for far more reach by thinking beyond the FB prison.