I'm a mentor for one. But haven't gone through as a startup
Or is your point that accelerator programs are aimed at companies in a particular stage and consumer apps don't need help through that stage. Surely the programs aren't that long and the next big thing could easily benefit from many of the benefits like networking and exposure?
If they just let you alone and let you build, what value would they be providing?
The value of an accelerator IS those mentors that harass you, ask you what you're building, and force you to challenge your assumptions.