sure, call it entertainment rather than social. very fair comment, but that is not a distinction this paper is making. the paper is also talking about tiktok too which falls into the same entertainment category.
i feel like the underlying thesis of this is maybe wrong. someone closer to the methodology would know better but here is what i see:
(1) Meta and Google have seen their growth slow (not shrink) because they reach virtually the entirety of the online population, especially in the US. Meanwhile their time spent metrics continue to rise.
(2) Reddit is called out as a modest grower but its usage has more than doubled in the US since 2021 from 90M to 170M (according to emarketer).
Doenst mean the conclusions are wrong (i agree with it on polarization) but the growth measures seem to not reflect reality.