It makes sense, Dr Mario is a character who is outclassed by many. He has some things going for him such as his Frame 3 Up B OoS option, having Mario's frame data, and a great set of good kill options (Up B, Bair, Dsmash, Usmash). However, Dr Mario's weaknesses are glaring. The obvious one is his recovery, he has bad horizontal speed, with two bad recovery options of Super Jump Punch and Doc Tornado, Doc's Super Jump Punch doesn't have the reach Mario's SJP has, while Doc Tornado can be punished if used near the ledge, this leads others getting to edgeguard Doc easily while having arguably the second worst recovery in the game. His main weakness is his weak range and speed combined. There is a reason why every character that is considered top ten with the expection of Rosalina, Luigi, and Ness, have good mobility to back them up. Doc has weak approach options becuase of his weak range and speed, while not being able to force apporachs because of having a projectile that bounces over characters. His matchup spread is also bad. Doc struggles against the top and high tiers in the game, he loses to Sheik, he loses to ZSS, he loses to Fox, he loses hard to Rosalina, and others such as Ness and Meta Knight. There are also many things his counterpart Mario can do that Doc can't, other than the obvious better mobility and recovery, Doc can't double Bair on a single short hop, set up jab resets with nair and jab (Doc's jab cannot continue jab resets), Fsmash not having the range of Mario's Fsmash, weaker combo potential, and more. The final nail to the coffin is results, Doc has none to speak of. He has Rice, but Rice also plays a lot of other characters as well.