They actually messed up the basic concept of a patent pool, and that is the key to their failure.

They didn't get people to agree on terms up front, they made the final codec with interlocking patents embedded from hundreds of parties and made no attempt to avoid random outsider's patents and then once it was done tried to come to a licence agreement when every minor patent holder had an effective veto on the resulting pool. That's how you end up with multiple pools plus people who own patents and aren't members of any of the pools. It's ridiculous.

My minor conspiracy theory is that if you did it right, then you'd basically end up with something close to open source codecs as that's the best overall outcome.

Everyone benefits from only putting in freely available ideas. So if you want to gouge people with your patents you need to mess this up and "accidentally" create a patent mess.