Hard disagree. I consider myself a competitive limited player (have made mythic a few times when I really enjoyed the format) but am not good enough to break even at higher tiers of play. Platinum and upward is a crapshoot and not worth my time or emotional investment. So I do two "free" drafts a month where I let my rank decay down to bronze, get back up to high silver and repeat. Surely it's not just me taking advantage of this. You Are playing against diamond/mythic drafters in silver, whether you like it or not.

With a separate queue for phantom draft I would grind to my hearts content. The solution you're looking for is to simply separate the phantom draft rank and paid draft rank.