For a public player it's easy to just take a quick glance at competitive TF2 and think it's crap. In the end, most arguments are moot, because they have never actually played it themselves.
Arguing which style of play is better, public or competitive, is just retarded. If you're the kind of guy that just wants to relax and do whatever you want, maybe don't have time to play most days a week, fine, play on public server. If you feel like pubs aren't much of a challenge or you just want to play in a truly organised team, play some scrims. Just because you prefer one style of play, doesn't mean you have to give up on the other. Most competitive players pub regularly, I do too.
Arguing that competitive players somehow are loud mouthed, rude and not very polite is also a matter of being mis-informed, or just having a bad experience. If you have happened to have read the Gotfrag forums, it's troll heaven and shouldn't really be taken seriously, just as the Steam Forums have nothing to do with the average public TF2 players mental abilities.
I mean, I love you all, but it's amazing how many people seem to think competitive TF2 is some sort of secret e-peen boasting club where you're not invited. All you do is play an organised game against another team. You play with friends and have good time, micspam in the warmup time and goof around. It's not super serious.
Lose the idea that competitive TF2 is a different game because it's not. The only practical difference is that it's played with smaller teams and without crits, that not all public players like either way.
Now onto the custom maps matter ^_^
In a play style where you want the most organised and skillful team to win, you usually want to play on a map that both teams are equal on. On a brand new custom map, you usually can't play as well as you want to, and working out strategies is hard. And you usually don't want to wait ages before everyone has finished downloaded the map.
It's easier for a league to organise something or hand-pick the really good stuff. ETF2L has been really lazy with that, and I know American organisations have been too. There is a custom maps cup being started here in EU soon though, so then there will probably be some feedback.
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Some CTF related talk then
The biggest reason CTF isn't played is because of the maps. Most maps are, excuse me if I come off as rude, not very well designed. Turbine is the only CTF map this far being played at all competitively, and only in EU.
Then why is Turbine such a well played map (even if it's only in EU) ? It doesn't have a very interesting layout, it looks pretty dull and has its flaws.
It's because of the size. Most CTF maps consists of a million small rooms with sharp corners, or the opposite, sniper heaven. And because of the smaller size, you can afford to move your team out to middle if you need to, and quickly fall back to defence if a spy has got your intel or they're pushing.
If you play 2fort, you need an engineer to cover the base (as it's very easy to get past the enemy team usually, unless they're all turtling) which is boring both for the poor guy being alone in the intel room, and for the other players because the game turns into a turtle fest. If you play turbine competitively (it's usually played most caps in 30 mins) you often end up with 14-8 scores, where as you play 2fort against an organised team you're lucky to get more than one cap.