Some ideas are tarpit ideas until enough people get stuck.
Location estimation (figuring out where you are) based on indoor WiFi / BLE is one example. Compared to 15 years ago, we have (IIRC - I don't work in this space) super-precise timing API from the modem, and there has been work on the reflections issue (the two big problematic things that non-RF people typically miss).
I did a project on this in like 2010 as a student hobby project. It wasn't accurate, but I also had no idea what I was doing. I mostly did it in a naive way, where I mapped out signal strengths in various rooms (it was dorm floor, 2 rooms shared each) and then trying to figure out where I was based on it. As a non-CS student I thought it was cool......
I think there is a difference between ideas that are based on a fundamental misunderstanding of how the world works and ideas that we do not currently have the capabilities to solve.
What about multipath? Is that not an issue at wifi wavelengths? Or is that a sub or superset of reflections? It was quite a long time ago now that the first "proof" that one could use leaky WiFi to "see through walls" and observe people moving around inside a building from without.
Participate in a transmitter hunt (also called a foxhunt or a t-hunt) where the organizers or the people hiding the transmitter know their stuff. Reflections and multipath can lead you miles away from a transmitter location.
Anyhow, someone asked me if I knew how to do this without consent once; that is, if I knew how to track people in a building without them knowing. This was 8 years ago or so. I had hoped saying "that's not possible" would dissuade them, but instead they just never spoke to me again.
Oh yeah, multipath is the term I was thinking of. As I recall, the issues were that a "longer" path may have a stronger signal than a more "direct" path, and that a straight line of sight path is not a given.
Location estimation (figuring out where you are) based on indoor WiFi / BLE is one example. Compared to 15 years ago, we have (IIRC - I don't work in this space) super-precise timing API from the modem, and there has been work on the reflections issue (the two big problematic things that non-RF people typically miss).