Wrong. Dexos1 oil is always SN/GF-5 as a baseline, all three specs exist together for all oils.
Umm, no. There is a thread here that shows certain differences, and I don't think I've ever come across the claim that they were the same before.
As for the conspiracy theory that conventional could meet dexos1 but no one is trying because they want to sell their synthetics and blends, I'm skeptical. SOPUS may not want to. XOM wouldn't, either. But surely, someone would want the opportunity to take a bite out of Pennzoil's lead in conventional sales, and a dexos1 rated conventional would be a useful tool in that regard.