"Many people paying a little bit" certainly works but it's really hard to pull off without funding, an
extremely compelling product, or some kind of brilliant viral growth strategy because you have very little room to spend on user acquisition. That's why investors in a product like this want to see early growth metrics that are on
fire. They are looking for something that can rocket up into millions of users, so if your growth slows down too much as you reach 100k users or whatever, investors will start questioning whether the market is big enough or whether the product is appealing enough to go the distance.
If you make something people will pay more for, it's just a very different calculation because you then have the potential to sustainably convert capital into growth. It allows you to grow more under your own power through sales and marketing rather than relying so much on virality.
For this reason, the GarageBand comparison isn't really helpful. Sure Apple could make a lot of money with that strategy because they could easily market it to millions of people. A new unfunded startup doesn't have that ability.