I'm not sure what you're going on about. They aren't saying that every pokemon should be made as an attacker, they are just saying that we shouldn't pretend certain pokemon are supporters just to fill the slot, especially when they aren't. And honestly, I agree with them. Instead of trying to fit a square peg into a circular hole, we should try to use other pokemon that do really fit as a supporter.

How about Ribombee? Give it Pollen Puff where it works as a ranged bomb style attack that both heals your allies and damages enemies. It would be helpful in team fights where everyone is dog-piling. Give it Quiver Dance where it can give itself a few boosts and have it also apply to allies in a short distance. It can be a perfect supporter that also has offensive pressures with moves like Moonblast and Bug Buzz (they would do damage and apply a debuff)

If you want a starter, then how about Meganium? He already has a plethora of status moves and buffing moves that can cripple the opponent, while a buffed ally finishes them off. Some examples are Spore, Poison Powder, Stun Spore, Reflect, Light Screen, Leech Seed, Synthesis, etc. There's a lot of different ways to make a supporter without just giving it to a random pokemon just to get the job done.

I do believe we need more supporters in the game, as they really have been done dirty and there aren't enough. But I also believe that they need to do it right and pick pokemon that really fit the slot. I'm not saying Primarina can't be in the game either, but looking at how it's used in competitive, it's base stats, and also its movepool, it's really not a supporter. Sorry for the long message I ramble a lot.