I think the main problem with rock types is that a lot of them are built like tanks when their type don't allow them to act like that. Generaly the best (or half decent depending of the generation meta) rock types are the ones that have relatively good offensive stats like attack or speed, like aerodactyl, lycanrock day/dusk, archaeops, nihilego, glimmora or kleavor. Even the slow tanks that are useful are because they have good abilities or moves, like tyranitar sand stream or garganacl salt cure.

The same happens with ice types.
Ice types are worse because they can only resist themselves while rock have a handful of useful resistances. Somehow gamefreak decided to desisgn a lot of potentialy good ice types as slow tanks when ice is only useful offensively. Avalugg and beartic are doomed to the low tiers while galarian darmanitar (a stupidly strong fast attacker) shares a tier with legendary pokemons.

Rock types were some of my favorites until I actually tried using them in battle.

It all went downhill from there.