It also states that it's for the purpose of promoting the creator's content on Patreon. For example, showing a thumbnail image of your video on another page as a recommendation would count as a 'derivative work.' Without this right, it would be virtually impossible to get permission from the creator for every instance in which Patreon wants to promote content in a new way. Also, it seems that the creator on Patreon would continue to benefit when Patreon earns value on the content.

Facebook, on the other hand, has numerous ways to benefit that don't proportionally benefit the creator, including from indirect revenue sources like advertising and data enrichment that don't flow back to the creator in any way. I suppose this is alright when you are just showing cat photos to your family, but it's quite different when you are basing your business on someone else's market-dominating platform with large negotiating leverage. And there are known cases where Facebook has been known to very liberally appropriate ideas from companies that are competitive with them (e.g., Snapchat).

It states clearly that it's also "to allow us to operate Patreon, promote Patreon, ...".

So if your content would make a good ad for Patreon, you've given them permission to use it without compensating you.

but... sublicensable?

I don't know what you're asking. It says "sublicensable" in there, yes.

I think he means that's the most unacceptable from the bunch

Sublicensing is what legally enables things like rich media link previews (the kind you see on Facebook and Twitter) or APIs to exist. Yeah, theoretically they could use that to sell content, but in practice it's generally used to make the web more interoperable.

I think it makes sense if the business relationship is actually artist <--> patreon <---> consumer. The client pays patreon, so patreon must sublicense the content to him. Otherwise I'm lost.