[Finwe]

Ah, but if Aragorn and Faramir had gone with the Fellowship into Mordor, Minas Tirith would have fallen. No Rohirrim would have ridden to its aid, since they would have probably been annihilated by Saruman's Uruk-hai hordes at Helm's Deep, and the Corsairs would have set upon Gondor from the harbor. Boromir would not have been able to hold Minas Tirith against such odds. As it was, the Citadel nearly fell, even with Gandalf there.

The Fellowship would have been hard put to stay out of the sight of Orcs when they got into Mordor. Even Frodo and Sam had to think quickly to deal with the Orcs that spotted them, even while those Orcs were "draining" out of Mordor.

Having Faramir go with the Fellowship just wouldn't have worked. The Fellowship had to break. Aragorn, Legolas, and Gimli had to be at Helm's Deep. They had to go on the Paths of the Dead. Merry had to be with Theoden and Eowyn. Pippin had to be in Minas Tirith with Denethor and Faramir. Frodo and Sam had to be with Gollum, in Mordor. Everyone had to be at the Black Gate to divert Sauron's Eye, otherwise Frodo and Sam wouldn't have made it to Mount Doom.