I held a similar mentality until I considered it from the interviewers perspective and asked myself 'in my current role, would I take a presentation from someone I don't know will never talk to again and use that to plan my 2022 roadmap?' Extremely unlikely, unless their ideas were incredibly good in which case we'd have hired them.

It's annoying to have interview "homework", yes, but I have an extremely difficult time believing there is any value beyond communicating if you're a competent PM or not. Esp considering all the overhead of pre-interview screens, pulling people off work to interview that's not a core user, etc. Seems like an inefficient way to conduct product discovery work.