There were about 3 mods who spent all their time squashing bots. Look at it now -- that's the level of bot traffic they had to deal with, for years. The mods had zero access to administrative functions (e.g., ability to add new mods, change the software, limit things so that the bots couldn't get in so easily, etc.). We were basically helpless, and all we could do is keep eliminating bots. It got tedious. Things finally got to a breaking point when the mods' ability to search for individual members was disabled. That meant they had to eliminate bot posts one by one, and they could only eliminate them if they saw them. So their tedious job got even more tedious and difficult.
We took a poll, and a lot of people said it was the time to go. Plainview got this forum up and running, and within a couple weeks, 96% of active TXB members had joined. So Union is essentially the surviving members of TXB in a new skin.