just because you cannot Play a champion or Play against him does not automatically dominate his entire existence. if you suck on singed, then it does not make him bad as a champion. it simply means you suck at playing singed. the reason why so many people get high with him is simply because singed has a fuck load of indepth to learn.
if you want the fairest comparison to what playing singed feels like then i'd give you shaco. he's all about mindgames, positioning, catching someone off-guard. baiting, proxy-farming. singed sucks as a conventional champion yes, but that doesnt mean he is unviable whatsoever. hes just different, and that is a good Thing. that is why people will Keep screwing everyone over with him and get to high elo, exactly because of the noobs thinking "oh yeah, singed is shit, ez win" then they lose and get tilted asking themselves just how it happens, and the answer tilts them even more until people are so raged that they cant even last hit against him and will do stupid mistakes like chase him because they desperately still claim on the thought that singed is easy Food for elo.
so my advice is, stop underestimating him so much, learn him, learn his Counters and weaknesses, then open your mind up to other possibilities than your own egocentric opinion. as i said, just because youre bad at something does not make it bad as a whole.