You forget that the lord is located in the enemy's spawn, you are required to take down the gate, kill the guards, and solo the lord. During all this time, the announcer is spamming that there's someone messing shit up. In tournaments, the Guild Lord is all or nothing. Even if he's comparable to Svanir or Chieftain in difficulty, the risk versus reward isn't enough, so no one bothers.
If you wipe on the lord, you lose the game, unless you already have a huge lead. If you already have a huge lead, why risk it all for minor rewards? There's no point to it.
Again, this is all for tournaments. For Hot join, it's a nice fun little thing.