i am assuming that it is 1 or 2 teammates of this and not a full team of them, and it is in ranked modes
if this was players who only excessively paint vs players who excessively dive and flank, it would be a much more even match. with it being players who just paint everything as much as they can and only slowly move up and only to paint more vs players who excessively dive and flank, the winner easily goes to the divers. in both cases, these players are either unaware of the objective or just not caring about it, but the thing about the divers (i guess im just calling them that now) is that they don't need to care about it. for the painters to be useful, they need to paint around objective and their teammates, but the divers just need to go to the enemies. this means that you can just play around them and support them doing this so that it is actually successful, but with a base painter you can't do that because half the time they aren't at objective or even near you at all, and if you could support and help them it doesn't actually do anything, you just become a base painter with them. even if the base painter farms specials, the only one that would be somewhat good is missiles and that is only going to work for a portion of the match, because when they run out of base to paint, they can't keep moving up because they will just keep getting splatted. sure, the divers are going to get splatted a lot, but that can happen a lot less if you help them fight by either dealing chip damage or painting an area around them so they actually have a good place to fight. plus, both sides don't offer much at all, but this type of player can still be played around. the difficulty with it is that you have to play around that player's pace and not your own to get anything out of it, but you don't get anything out of base painters besides special spam and a bunch of paint at most up to mid which at least 80% of would not be relevant to the game.
i was going to ask what would happen if you put a team of completely aggressive enemy rushers vs a team of completely passive base painters who would win, but the answer is nobody. both won't play objective because all of the divers just go for splats and the painters literally can't play objective because they are too busy getting splatted and painting base.
we all been forgetting the real worst type of teammate though, which is the player that excessively does objective. they only try and ride the tower at all times, only sit back and paint zones, always grabbing rain maker no matter what, or using ink brush and rolling around trying to spam power clams in the enemy basket. i honestly have a problem with these types of teammates the most, because 1: how are they in my rank 2: i am so sad that they don't know how to play this game, it's so fun and cool they are missing out on a lot and 3: wait a minute this was a series noo i just lost my streak! you might be able to argue that you can play around this player just as much as you can an enemy rusher, but i just find it so much harder to do that for these types of players.