>>53046953This is largely because Stone Edge is a crap move.
If they ever decide to fix that by buffing Stone Edge, or by giving Tyranitar Rock Slide or even Power Gem, it'll perform much better, though without checking I don't know if it'll outperform the other rock types you've listed.
The only reason Gigalith and Tyrantrum do so well is because they made Meteor Beam absurdly powerful. This is Niantic's idea of balance, strong Pokémon get weaker moves, weaker Pokémon get strong moves.
And then legendary Pokémon that drive raid pass sales with good stats get good exclusive moves (usually, Latias/Latios got shafted).
