it would take a lot of extra code to add this ability to one relay but it would only apply to the ones that have it and have it activated.
i would oppose any such thing on the basis of performance alone let alone creepiness.
most relays don't have any facility to reveal the number of times events have been delivered at all let alone narrowing it down by anything better than IP addresses.
so, yeah, nah. and good, because fuck that shit. if you can monitor everything you can censor it.