Because Pokémon rarely makes a card that targets specific other cards. Now, before anyone says this, I know there are cards like Bonnie that do this, but it is still not common. I have noticed that it is becoming more common than it used to be though.
Actually Pokemon been releasing quite a lot card that target specific card like
1. Victory Piece for Victini EX
2. Crystal wall for black kyurem EX
3. Crystal edge for white kyurem EX
4. G booster and G Scope for Genesect EX
There are more but not really want to write it all
The rest card that not so specific single target like
1. Counter energy that work on non EX/GX Pokemon
2. Specific type special energy like strong energy only work on specific type pokemon
3. Beast ring for ultra beast only
4. Nest ball which search for only basic Pokemon
5. Supporter like Elm lecturer search for pokemon with 60hp or less
6. Pokemon tools like body building dumbbells only work on stage 1 pokemon