I think they've been substantially lowered; though. I've seen more Beedrill, Tranquil or Pidgeotto than I have starters. It was similar when I decided to hunt for Totodile; I ended up giving that up after a fruitless few days. If Turtwig is time-of-day locked and at a spawn rate of; say 1%, then it might be one I can't find due to time zones.