Server and game populations will constantly be fluctuating. These fluctuations will affect each server differently and each player differently. A player who always plays during peak hours won’t see as much of an impact from the fluctuations as someone who plays during off-hours. But either way, without cross-server OPR, many players won’t be able to access this game mode or at least won’t be able to play it nearly as much as they’d like to.
As more content gets added, the playerbase will become more and more spread with what content they’re doing. Mutations have been a great example of this. So many more players are becoming invested in dungeons (both normal and mutations) this week that it’s had a very significant effect on OPR queues.
OPR is very dependent on what time you are trying to play. If you are someone who plays during off-hours, you may never be able to play OPR due to your server not having enough people playing at the same time as you.
All 3 of these factors would be solved (or at least heavily mitigated) by making OPR cross-server.
OPR has no influence on territories so there’s no reason to have it be server-specific.
I think the most valid argument against cross-server OPR is that it’s nice being able to play against people you know and/or are familiar with. It builds more of a community within your server. This is valid and I agree with it, but it’s not worth not being able to play the game mode.
For the above argument, if AGS is willing to implement a more complex system, what could be done is that there is a server-wide toggle that switches a server to/from cross-server and server-specific OPR. This toggle would be based on something like current population or current number of players queueing. I can think of many potential ways to implement this. They wouldn’t be trivial, but it would preserve the “server-specific sanctity” when possible and then provide the faster queues / any queues when the server cannot support its own queues.
Imo, that system would just be unnecessarily complicated to implement and my vote would just be to make all OPR queues cross-server (ideally the whole region and not just the worldset). But I did want to acknowledge that factor and maybe someone else has some smarter ways to deal with it that would work well and not be too complicated.