Currently you can que into Cyanide's open ladder with a custom team of your own creation. This means you can make an all linewoman Amazon team with blodge, 4 re-rolls, and an apocathary for only 1020 TV. You can make a Lizardman team and give all the Saurus block, which is usually hard to obtain. Another possibility is to create a normal Chaos team but stack kill skills on one player without drastically raising the TV, giving you a huge advantage.
Not only is this a turn-off to any new player who probably won't recognize what's going on but it really destroys a good deal of what makes this game fun, which is leveling up. Proper SPP allocation also takes some amount of skill and allowing custom teams destroys that, and having that level six get injured will have far less meaning if you can just re-make the exact same team.
The game already recognizes in team skill descriptions that part of the game's balance is in how some teams are weak early but strong later, and custom teams throws this completely out the window. Custom teams should really stay in custom leagues and not be represented in open ladder, or it will really destroy the balance of teams we already see.