Not to counterbelabor the point, but that’s not the ONLY reason Gandalf gave for “Let’s not take Glorfindel”. The passage has been quoted earlier, but the gist is along the lines of “Yeah, Glorfindel is pretty mighty, but if it comes down to us needing to be pretty mighty, we’ve already lost.”
So… again. There’s not really any point to bringing him. Seriously. How much fighting did the company actually do, and how much of it actually accomplished anything?
Fight #1: Moria, Balin’s Tomb. Company wins a brief respite, then has to run away. What would have changed if Glorfindel had been there? Nothing.
Fight #2: Moria, The Bridge of Khazad-Dum. Gandalf sacrifices himself to defeat the Balrog. What would have changed if Glorfindel had been there? Likely, nothing.
Fight #3: On the slopes of Amon Hen. Boromir dies, the only reason the orcs don’t overwhelm and kill the rest of the company is that they seem content to carry off Merry and Pippin. What would have changed if Glorfindel had been there? Likely, nothing.
Fight #4: Cirith Ungol. Sam defeats Shelob with Sting. What would have changed if Glorfindel had been there? Likely, nothing. Except perhaps Glorfindel’s demise. (This stuff is heavily implied in the text).
That’s it for fights on the way to Mordor. There are some fights involving other members of the Fellowship, but they don’t impact Gandalf’s “plan for getting the ring to Mordor” - which, make no mistake, is what the Fellowship, by and large, was selected for.
Amusingly, from this perspective, Merry and Pippin’s most valuable contribution to the Fellowship is, in fact, being CAPTURED by Saruman’s Orcs at Amon Hen, because they effectively acted as decoys for Saruman’s raiding party, who otherwise might very well have captured Frodo, or at least, Sam (Which, in the long run, would have been just as bad.).
That’s it. That’s all the fighting the Fellowship does as a fellow