Who says Dr. Mario is bad??

I never understood this sentiment, as basically anytime I face a Dr. Mario when I go online, it's basically a free win for them when I can easily or at least more reasonably beat types like the Aegis, Cloud, Sonic, Game & Watch, and a bunch of others. However, Doc and Sheik in particular seem to be two of my largest harbingers of doom. Not only have they almost always beaten me when I come across people who play them, but I also usually follow my matches with them with complete losing streaks that quickly make me want to turn the game off. Doc in particular always seems to have hitboxes that both are waaay larger than his body and come out waaay faster than they should, not to mention the existence of pill and cape in his kit.

Seriously, is Doc actually better than people say, or do I just suck that bad at Smash? All the losing streaks I've been on begin to mess a bit with my depression, which makes me feel like whatever progress I had before was undeserved.