I also mentored for Plato and quit for very similar reasons. When I started, I thought I'd be helping people who are underrepresented in tech, or even just people who had interesting goals that my experience or coaching might help them achieve. Instead, I found people whose companies were paying Plato to give them a service, weren't particularly self-motivated, and were highly traditional in their backgrounds. Worse still, they would schedule my calendar then cancel at the last minute, and Plato didn't seem to discourage this, even though they required me to block my calendar. Then they wanted me to spend my time writing a business case study that they could use to promote themselves. I actually think mentorship could be a great place for innovation, and I could even see "volunteering" or doing 'pro bono' work, but not when it has almost zero return even from a feel-good standpoint.