There's multiple games I call friendslop despite them being generally well made because they have singleplayer balancing issues that get solved by multiplayer. Also I don't really have a better term.

Valheim for example gives many bosses too much health so they're a slog in singleplayer but fine in multiplayer. Hytale recently added their first boss fight and it has the same issue, hopefully they fix it.

On the other hand, Terraria does a very good job with balancing bosses for both single and multiplayer. I've beaten the game in master mode several times both with friends and alone and no boss has felt overly easy, difficult, or boring.