I think the big weak link/Plus Factor for something like Patreon is that it requires a strong sense of salesmanship if you're going to pull it off successfully. I think the best Patreon success stories have that common thread of the creators being engaged with the community, happy to interact with them, establishing a relationship, in addition to just cranking out content. People who contribute to Patreon are expecting the creator to be answerable to them in some way, now that they're paying directly out of pocket.
For some people, especially the ones with really good PR skills, this is an amazing, low effort way to get funding directly from fans. If you've got the charisma, online or otherwise to get people excited about supporting you, and actively maintain and nurture those financial relationships, this is a fantastic idea. For other people (like me) the idea of having to engage with and establish all those relationships, keep them excited and enthusiastic, play up to their questions and expectations... I'd rather undergo a root canal. I know not everyone would look at it this way, but the one thing that makes me really leery of things like Patreon is just how quickly it can degenerate into toxic fandom, where the people paying the bills can now, legally, say "Hey, you owe us!" because you do. They're paying for you now, this is an actual business transaction.
I think it's amazing when creators have the kind of people skills required to keep Patreon subscribers happy and more than willing to keep donating every single month. But that's totally not me. As an introvert, the idea of being directly answerable to so many total strangers, now due to financial obligations, is terrifying. I much prefer freelance jobs where someone just says, "Hey, I need this by this deadline," and I do the work, submit it, and get paid. There's no need to entertain, engage, or make sure the person came away pleased with the interaction, or suffer the wrath of complaints on social media of being an "ingrate to the fans."