I think it's a deliberate design decision that only moderate SA pokémon learn this move.

At least Plusle and Shroomish/Breloom have decent STAB elemental attacks available. Plusle's SA isn't that bad, actually, especially considering it gets a boost in 2 vs 2 battles if teamed with Minun.

Plusle + Fake Tears + a couple of thunderbolts will deal with most non-ground opponents.