Sev, you joined the server with the sole purpose of raiding us. You're going to join the next server with the sole purpose of raiding, uh, probably us, again. I don't think there needs to be much explanation of why they don't want some stalker friend that gets some crazy boner from blowing up an unfinished faction that's attempting to have fun.
You apparently didn't realize you seem to be the only one who did this stuff. None of the other factions (I'll assume you'll put it this way) "played properly." They weren't total bloodlusting richardheads like yourself, who seem to believe the only source of "fun" is ruining others' fun.
I don't give a stuff about "oh it's factions griefing is allowed." Okay, cool, it's allowed. I'm sure the server owners still heavily frown upon joining their server with the sole intent of driving out everyone. No one else (including us) seemed very happy about it either. Just you. Only you.
And like you said, you'd be back. You'd keep hitting us and hitting us until we're permanently gone and sick of it, so don't say anything about how we should keep trying, because there's seemingly no point.
tl;dr Just because what you're doing is allowed doesn't stop you from looking like (and being) a total fun-killing jerkass.
P.S. I wrote this at 7:30 AM goddamn I'm tired