I disagree with that notion. It wasn't until Rainbow was introduced that parties suddenly became HUcast + FO. Even prior to that it was not uncommon to see optimal parties utilizing HUcast + 2 RAcast. It really depends on the area you are playing in. Dark Flow gave hunters the ability to one or two shot aerial spawning enemies and to combo kill single targets with ease, which is arguably what they should be able to do given their class. As a sword it was great too, but again RA's with Charge Arms and Baranze Launcher or Hell specials were typically just as or more efficient, which again makes sense given the purpose of the classes.
I don't see how vanilla's balance is better. Pre-Rainbow, HUcast, RAcast, FOnewearl, FONewm were all viable candidates. You could argue for Hucaseal/Racaseal in specific quests. Now its basically the RAcast show + anything with Shifta/Deband.