I feel that a dissenting opinion needs to be presented in case Zwift are actually considering implementing this sort of thing. Please don’t take it personally. I may only speak for the minority.
I oppose the idea of putting riders into categories on two grounds.
Just because a rider is capable of a certain wattage at threshold does not mean that rider will be riding at Zone 4 today. You will likely miss out on the chance to make new friends if you assume otherwise. For all you know, you might have had a nice two hour ride where you were at high tempo, and your new buddy was at low endurance or even recovery pace. Project this out to more riders and you can see how pigeonholing people can make things weird.
It takes something away from the social aspect of this as a social game. In real life, nobody has their FTP stamped on their back in a ride. Even in races where there are categories, people still don’t advertise their relative strengths. It is the task of the individual to pay attention and find out by observation what the situation is. It’s the same thing over the course of time when you enter into a new location and meet riders. You find out who the people in your relative strength ballpark are. You find out a lot about people by observation.
I would prefer if Zwift were like that. I have now logged 1500 miles on Zwift and I can safely state that I still prefer it that way.
If you want to ride with people at a certain pace, then set up a forum or a signup place where these kinds of desires can be discussed, along with riding style (competitive, stay together, length of ride etc.) This is already happening on FB and it’s only a matter of time before it happens on “My Zwift” as well.