Long story short, I think Smogon are a collective bunch of quacks. Their bans often seem like arbitrary decisions based pleasing the whining masses ("Waah! I can't beat a Kingdra with Swift Swim, so it shouldn't even be allowed!"), or are just plain ridiculous (Excadrill? Really?)
If the makers of the game didn't want people to use the combos that debuted in Gen V, then they wouldn't, for example, have given Politoed Drizzle in the first place, and just left that apparently too-powerful ability with a Legendary Pokemon (whose banning is more justifiable, due to superior base stats, but still IMO unnecessary).
Smogon (and websites like it) ruin the fun - no, the point - of multiplayer in Pokemon by making these additional rules. So what if you get smashed? Alter your team and smash them back! Many Smogon players say that Swift Swim + Drizzle is 'broken', but Thunder and Hurricaine never miss in the rain, which takes care of just about every water type (including Ludicolo) that are 'too powerful' for use. Even perma-weather can be shut down by other forms of perma-weather. No Pokemon is unbeatable, and no strategy is perfect, therefore nothing should be banned. Players don't need to be told how to play their own game, and can govern themselves.
For these and other ridiculous enforcements, click here: Smogon University's Black and White Ban List
RE-RE-EDIT, 6/6/12
Many people in this thread have done nothing but bash my opinion and tell me just how wrong I am, while praising Smogon's streamlining and cleaning up of the 'Metagame'. According to Wikipedia, "Metagaming is a broad term usually used to define any strategy, action or method used in a game which transcends a prescribed ruleset, uses external factors to affect the game, or goes beyond the supposed limits or environment set by the game. In simple terms, it is the use of out-of-game information or resources to affect one's in-game decisions." In other words, 'metagame', in this application, means 'house rules'. House rules are fine, as long as everyone knows they're house rules. When house rules start being so widely accepted that people think they're actual rules, there's a problem. I'll use the game Monopoly, for example. It's quiz time!
1) Does a player receive money for landing on Free Parking from a pool in the center of the board?
2) Can a player purchase properties before they travel around the board and pass Go for the first time?
The answers, according to the rules of the game, is no, but both of these house rules are so popular that many believe and that they are actually the rules of the game. That is perhaps one source of my issues with Smogon: they post their clauses and banlists which many people (including non-Smogon members) read and adhere to. These non-members may naively think them 'official', somehow, and change the way they build their teams around that. Or, a Smogonner, used to playing with certain rules, may attempt to 'help' someone by letting them know that they can't use (ie) BrightPowder because Hax items aren't allowed. I've seen it here in the forums, even. Someone will say, 'I need advice for team building', and then get a response like, 'you can't use that; it's banned', but neglect to mention that said ban is only for Smogon's gaming community.
At the other end of the pendulum is the part of Smogon's community that truly makes me hate them: the members of said gaming community who believe that they are better than everyone else because they follow Smogon's rules, which are absolutely infallible. You can spot them commonly spouting phrases like 'lol u cant use that cuz its banned u noob', or 'you'd better listen to and respect me cuz (unlike you) I know what I'm talkin' 'bout'. Many of them think that because Smogon's members have play-tested and voted their rules into practice, that it means they are the authority. That's flawed logic though, like a rebublican politician saying, 'nine out of ten of my fellow republicans think this bill is good, so it should be made a law due to its 90% approval rate'. I've also noticed that these types seem to get extremely defensive about anyone disagreeing with Smogon, as though doing so is tantamount to insulting their Momma. Through the course of this thread, Vhaziphor introduced me to the term Scrub, which I'd say sums up the type that I'm ranting about. (This video also is a good example, though much snarkier.)
Far from 'cleaning up the metagame', Smogon has cluttered it up with unnecessary rules that were never supposed to be a part of the game at all. Tiers restrict people in team-making by governing which Pokemon that they can use. Banning certain Pokemon based on their stats is silly, and banning them for being 'too popular' is outright ridiculous.
In short, I'm Anti-Smogon, and I'm as justified in being so as its frenzied supporters are of it.
On a side note: It's come to my attention that many people who support Smogon and other communities like it seem to freely use cheat devices and PokeSav to 'engineer' Pokemon that they can't normally get in the US (here's looking at you, Speed-Boost Blaziken), are shiny,
have perfect IVs, or whatever, without putting any effort at all into it. People who use this method of 'creating' Pokemon, rather than breeding and training them, are, in my opinion, cheaters. Call me old fashioned, but I've spent days chain-breeding Pokemon to get egg moves I want, weeks on EV training, and even longer chaining for shinies, so I simply have no respect for that sort of thing.
