I think you vastly underestimate Sonic. He is bad but he beats the characters that beat viable characters. Don't think just because Ike and Marth can stomp all over Snake, that they don't also get stomped by Sonic.
Its the same boat with ROB, DK, Peach, Fox, Pit etc. They are all more viable than Sonic, but still lose/go even with him.
No one in brawl is particularly easy to gimp or kill (outside of low tier). 9 times out of 10, marth will make it to the ledge and 9 times out of 10 his early kill setups wont work on Sonic either. This game is a big defensive struggle.
Marth and Ike rely on the same thing for safety. Both keep you at max range so they by the time you reach them, they moves are over. It just doesn't work against Sonic though, which is the problem they both run into. Marth actually does take an equal risk for whiffing his aerials because of how quickly Sonic can get to it. Being slightly wrong means you got grabbed, even if Sonic wasn't near you when you missed. Sonic, much like Snake or ZSS, has hitboxes attached to his legs where they really shouldn't be. Marth only barely outranges Sonic most of the time (in a matchup where its not humanly possible to space safely often) and sometimes is less range.
As for Wario vs DDD, imagine for a moment that you are examining the matchup with fresh eyes, without any preconceived notions that DDD is Wario's worst matchup. Would you still think DDD wins "for a reason" if DDDs are losing to Warios consistently? Any scientific approach has to accept the results of expiriments (even if with a "grain of salt"). I don't know the skill difference between Reflex and the Warios you are talking about, but it shouldn't be disregarded just because we've always viewed the matchup as bad in the past. Once upon a time Wario was seen as even with MK, but results proved otherwise and we adapted our thinking. We never want to look at just one result, but at high level play, a larger pool of players for each character can show a pattern. If Gluttony beat Atomsk and lost to Seibrik, Reflex beats 4GOD regularly and whatnot, the matchup doesn't look so bad at high level play does it?
For the record, I don't keep responding because I'm mad or I hate you. I enjoy a good debate, fight, argument, discussion or whatever. Nothing is more interesting than understanding why another person has a different view than mine.