Posit: there hasn’t been a sustained break out social app not funded by a big tech company since Snap?

What candidates come to mind from each of the following buckets?

1. Funded by big tech and sustained
2. Not big tech funded, fizzled out

Working on Emergence.

emergenceuniverse.com

1. I think Youtube is the deepest sustained impact
2. maybe not of its own making, but Vine was pretty impressive, all things considered.

𝖒𝖆𝖓𝖉𝖆𝖙𝖚𝖒 𝖆𝖉 𝖆𝖘𝖙𝖗𝖆

if we're going with platforms/protocols not funded by big tech but were "sustained", then phpBB, SMTP, mailing lists, and IRC are top of mind. 

I'd probably underestimate pretty much anything made past the 2010's as not having some moneyed interest behind it.