The roaming community is small and for veteran roamers, many of the above average roaming players and guilds are pretty much well known across all the servers.
One trend I've been seeing though, while playing and watching live streams on twitch, is that skilled roamers avoid fighting each other a lot.
They run around the map, bump into each other, recognize each other from guild tag, looks etc. and move pass or detour without fighting.
Then when they encounter a pug who might just be a zergling or a less skilled roamer, they jump on them and stomp them into the ground and thump their chest howling in victory.
The vibe I get from skilled roamers who avoid fighting each other is like "Hey I know you're good and you know I'm good. So lets not risk fighting each other."
Isn't it more exciting to fight another skilled roamer than to stomp on a pug?