One more reason why having multiple classes is useful.
The best speedruns you can get are either blm+brd or double blm.

If you cannot go as drg then just go as something else.
Or make your own party.

But it is a speedrun because its supposed to be fast. And if the party leader thinks that blm+brd is the way to go then so be it.
If you need alot of myth and wanna run 120 brays then ofc you want it to be as fast as possible.
A 8 minute run which is pretty slow would take you up to 8 hours more than a 5 minute or less run.

It has nothing to do with elitism but rather effectivity.