the only actual "problem" with WFH (actually a management problem, as with everything) is that people no longer have any concept of "business hours". just because people have access to their "office" all the time doesn't mean they have to work outside their 40 hours!!
if you email someone at 4:47 on Friday and then send another angry email at 8:13 on Monday you have not been waiting three days, you have been waiting 26 minutes
"why haven't these people been checking their emails regularly during their evenings and weekends: I do!"
[is quietly pushed off a cliff by persons anonymous]