So what happens if you choose to use Samus in the first match of a set? You have no idea whether or not your opponent is going to pick Dedede. So if they do you're screwed. You didn't decide to try the matchup. You just got screwed. So you can't go with your main in the first match. Now if you won a match with your main you have to switch to another character because if you don't you can get Dedede'd. So you can't use your main except as a counterpick. Which means for all practical purposes you can't main any of those characters. Whether or not this is a reason to ban the tactic is a judgement call but its not simply a matter of choose another character for that one matchup.
You're not understanding...it's not even auto-loss for the Samus user. People like Xyro, Bum, and Boss deal with these problems and worry more about GOOD players in a tournament setting as opposed to guys who CP D3 and hope for a free win. All of these character have options and viable strategies for dealing with this matchup. If there was no way around it, I'd agree with you. But people are beating the infinite, it's obviously not game breaking.
Technically, Akuma was beatable; being beatable isn't synonymous with being fair. The only reason it's not that big of an issue right now is because there aren't a lot of tournament mains who are affected by it. And a primary reason why people don't main characters affected by the infinite is because--you guessed it--they don't want to waste money losing to an entirely unfair tactic. Do you really think DK would have lower tournament rankings than Peach if he wasn't faced with an effective auto-loss every time he fights a Dedede? Granted, aside from DK, I doubt the unlucky few would do exceedingly well if the infinite was banned, but none of them are Captain Falcon-level bad. They would have a chance if it weren't for the infinite.
I honestly don't know much about Akuma so I can't really argue that. From what I hear, his air hadoken (or w/e) was broken and made the match pretty much unwinnable. Basically, he was made to be broken; he wasn't made to be even with the other characters.
At any rate, D3 is beatable. This is my point. It's not even an end-all thing if you're grabbed. Not every D3 knows how to properly do the infinite, if you're grabbed under...I think it's 50%...you can still escape, if you're near the edge when you're grabbed then you can autobreak it, and plenty of other things. Aside from that, Samus and Mario can easily play around the edge and bait grabs, Luigi can't be CGd so messing up the infinite once means no infinite for the rest of the stock, and DK has range to compete with D3...which is a terrible matchup without the infinite. It's a VERY different matchup and must be played differently, but coming up against a D3 as one of these 4...or 5...shouldn't be looked at the way you're looking at it.
It's the tournament organizers' choice to ban a decidedly unfair exploit instead of effectively denying several characters a chance. I don't think it should be our burden if it's directly caused by their rules.
If TOs wanna do it, then fine. But I'm talking about tournament standard.
Let me try to explain this in terms you'll understand.
Suppose tomorrow, a glitch in Metaknight's dtilt is discovered that will instantly kill Falco and Fox. What do you do? Do you concede that it's just your tough luck for maining Falco and switch to someone who can't be instantly killed? Do you push for a ban because it's a programming exploit that makes otherwise good characters completely unviable? Do you show them all how it's done and just "not get dtilted" in every match (After all, I hear you Falco mains prefer the air.)?
Lmfao @ this example
It'd prove even further that this game is a progamming failure on many levels for competitive play. You have a point, but SBR consistentcy would suggest that they'd leave this alone and just stamp it as "just another bad matchup"
Edit @ Hive: The thing is...beating D3 as one of these characters isn't rare. It simply becomes a campfest and if you can effectively camp D3, the grab is much less of an issue.
Also, you have to realize, you go into the matchup
already knowing what the D3 wants to go for. D3s become terribly telegraphed and, with 2 of these characters having excellent combo games against him, Samus having greater grab range, and DK having ridiculous KO power, you can take advantage of this. They're more of a slave to the infinite than you are.
Basically, know the matchup and get some experience. It gets much easier and much more bearable.