Riot must have changed the matchmaking formula last patch, because before then I never saw a bot in Dominion on account of high MMR. Now I'm seeing them all the time. It is painful to queue for 15-25 minutes and then have a game ruined by bots. It's driving people out of the queue either by dodging or going to other maps, which is making the bot problem even worse.
A temporary solution would be to make it so level 30s don't get matched with sub-30s. That wouldn't solve things (lower level players would still have to deal with them) but most of Dominion's dedicated players are long-timers that hit 30 a long time ago.
The best solution would be Riot finally sucking it up and having players just start at level 30 from account creation. As with any illegal product, farmed accounts have demand. So long as that demand exists people are going to cheat to make money off it. If Riot destroyed the demand, then the bots would evaporate overnight.