People must be including GBA backwards compatibility in their assessments of the DS, because it’s library is awful. Lots of gimmicky touchscreen games and lukewarm sequels. There are a few standouts (Castlevania, Ghost Trick, and a bunch of ports/remakes) but otherwise it was a letdown. Not a single good Mario, Zelda, or Metroid game was released during in the entire DS lifecycle. They managed to release one Fire Emblem game (a remake of the first, with years of map design progress unchanged). They had remakes/ports of old Square RPGs and Pokémon games.
The GBA on the other hand was held back by having only two face buttons.