Comment by 4bpp

I think your post hints at a general schizophrenia in the latest, culture-war-fueled push against Facebook. On the one hand, the public debate is still significantly dominated by the old guard of anti-Facebook activists, whose objectives can be summarised as "Facebook's power over its users must be reduced". On the other, the renewed interest in doing /something/ about Facebook in the wake of Cambridge Analytica and fake news (and, before that, cyberbullying, stalking, harassment...) essentially amounts to "Facebook's power over its users must be exercised to quell evil". More often than not, the two are actually diametrically opposed (as when quelling evil turns out to require an increase in power). A hypothetical actually usable decentralised social network would advance the former cause, and, as you pointed out, set back the latter.