I agree, a free tier is needed to get started. And you're right about a watermark being intrusive for that service, also. I just worry that so many of the things we enjoy will become unsustainable. People have to get used to the idea of paying if they don't want to eventually become the product.
It's interesting as a user to get perspective on these things. The ongoing human costs aren't as obvious as operating costs like hosting. Someone should do a "day in the life of a FOSS service" documentary...