From a typical game design point of view, that’s true, but ranged attacks and zombies only have a limited applicability, really the shockers and spitters aren’t even that great a match with being zombies. If zombies were a faction, they’d be like zerg, try and overwhelm you with sheer numbers, the best counter to this IS to keep your distance and not engage, it’s not even a question, that having been said, it’s certainly possible to deal with them as a melee specialist too.
I think balancing melee vs zombies is going to more be a matter of adding capabilities to melee that ranged combat can’t match, like knockdowns, pushing, etc, that let you consistently fight zombies one-on-one, where you generally have a huge edge, especially if you’re capable of kiting them.
I think scaling zombie difficulty makes more sense in the area of increasing zombie numbers rather than making individual zombies more dangerous, although I’m not particularly opposed to increasing zombie variety in general.
