One of the biggest (perhaps the biggest) strengths of iNat data is the sheer volume. With so many people plugging away at observations it becomes possible to do things that would not otherwise be possible, provided, of course, that the researchers are willing to curate the data.
I think it’s important to be clear that the data are not iNat’s actual objective. It’s about expanding public understanding of the natural world. The data are a bonus, not a primary objective.