replies to numbers:
1> constantly changing modes because another server changed them can lead to the infamous "bot fight" widley seen take place between Chanserv and Eggdrops because they are both set to enforce modes and both think they are right. No thanks.
2> Future to whom? .. how is services to know what is "in the future" to the ircds if they have offset times? .. no thanks, lets stick to the facts.
3> would cause undue desyncs IMO not to mention that the ircd should use it's own timestamp on the SJOIN so the events are not responded to out of order due to some latency somewhere. No thanks.
"As for what server admins can do in the mean time to resolve this, the simple answer is to make sure the server Anope is running on has an accurate clock by means of NTP"
Now THAT is the correct answer and it has always been the correct answer for many many years. Plus NTP is simple to use and mostly automatic. It's also conveniently the solution with the fewest variables.
Some things are simply required to function properly, in this case NTP. If you don't use ntp, expect desyncs ... it's that simple. I find servers like mine that run ntp don't have this issue.
If you are hosted on machine that you don't have root access to, tell the admin to run ntp .. it' something they should be doing anyway, especially if they sell shell hosting accounts. The best solution is not always the high tech or most complicated solution.