[AragornII]

If Gandalf had been with Frodo, how would they have gotten to Mt. Doom once inside Mordor? I know someone said that Gandalf probably had a different route, but once they were in, weren't like 10,000 orcs between them and Mt. Doom? If Aragorn and Co. hadn't distracted the Eye of Sauron at the Morannon and drew all the orcs away, Frodo and Sam might not have made it through.
Someone might have said this but if Aragorn hadn't gone to Minas Tirith by way of Rohan, he wouldn't have brought the Army of the Dead with him to Pelargir to fight the Corsairs. The Corsairs would have come to Minas Tirith and there would have been no hope. This is why Aragorn couldn't have gone to the Black Gate.