It's a lifeline for a lot of creative work that people will support but where there's no expectation that every content consumer can support it without transaction fees being insane and where advertising isn't a fit. Podcasts like Do By Friday, a wide variety of adult oriented artists, Youtubers who aren't viral, etc.
Patreon offers a way for people to use their money to say "I like what X is producing and I want to make it possible for them to keep making it available to the world."