Also the cost of wasting interviewing resources on people who, knowing the job is on-site, will interview solely for practice with zero intention of joining.
Would that not work the other way around too? People interviewing remote-only companies for practice when they have no intention to join. IMO, that's a lot easier too, since you can get a lot of practice time in without having to commute to places.
No interviews are onsite at the moment (at least in big tech), so at the moment no, but when things get better? definitely