Not sure why they do it myself or how prevalent it is.

Perhaps subletting rent stabilized housing when the price increases further? In this case it wouldn't be much of a problem.

I haven't seen any statistics, just some anecdotal evidence for absentee renters, especially in the past two years.

Regardless, ownership is obviously a bigger problem.

Because in some locations (c.f. London) this makes the asset far more liquid. Having renters requires you to engage a property management company and the presensce of tennants makes it harder to flip the property quickly if you need to get access to your stash of ill-gotten gains.

It is not just stories and anecdote, there are large portions of high-end London real estate sitting empty because foreign buyers often do no want a tennant.

Until you cite some statistics (specifically the residential vacancy rate), you are in fact just repeating stories and anecdotes.