alexmf2- This situation isn't hard. Communicate for Magnezone, Rare Candy into Magnezone, and Magnetic Draw in the hope you hit Emboar, Communication, or Junk Arm. Chances are you will. Regardless, what's going to destroy an almost fully setup field in one turn? That almost never happens. Tell me which is more likely:
1) Needing a basic.
2) Having a hand where you need a Stage 2 Pokémon and don't have an expendable Pokémon in your hand.
If you have "that 1-of Communication", you'll never have it when you need it. This is basic math - you have a 1/60 chance of a card in your deck/hand being Communication, so chances are you won't have it when you need it with only one copy.
You've seriously never seen Communication used for a basic? Quite honestly, I'm not even sure what to say to that. There are many, many turns where you need a basic. You make it sound like this is an uncommon scenario.
You make the argument Elm's wasn't played because it was a Supporter. Celio's Network saw an unbelievable amount of play in non-ex decks. It was basically a staple 4-of. It's PETM, but it also searches basics.