bountyquest (paid) - existed in early 2000's

patentbusters - ditto

Peer to patent - more recent

Patexia - still exists

article one partners - which still exists and pays

I don't feel like trying to hunt down the rest, but there are/have been at least 10 or so crowdsourcing attempts, some serious, some not so serious.

THe key part is recent changes in the law have given much more weight to community/public commenting on patents, so where these may have failed in the past it is possible for them to have more success today.

Further the patent climate has become more hostile towards bad patents in recent years, more so than at in point in modern history, this will also enable more possibility for success

Your assertion remains to be seen. There are still significant downsides to submitting prior art to the PTO that also existed when bountyquest was around.

The main serious issues are still the same, in fact:

1. If you submit prior art pre-grant, that's basically that. You don't get to argue about it, only the examiner does. If the patent issues, you've now lost a possibly valuable reference if the examiner didn't use it well enough.

2. If you challenge in any of the post-grant proceedings, you'll be estopped from suing on anything you raised or could have raised.