It's always been tacitly understood that different parties have access to different resources. So, if the party "just happens" to have Mass Resistance in store, then they can make a battle become utterly boring. Alternatively, you can design monsters that are basically impossible without Mass Resistance. This actually works if you're tailoring monsters for the party-it rewards players for their choices without threatening a TPK (because you know they have that choice). The problem, of course, is that any such monster inherently has to be ad hoc.
It's rather like having trolls that are entirely impossible to kill without fire or acid damage. If the party has access to fire or acid damage, there's no issue, but if you run such a troll against an all-melee party with nothing but sticks and stones, you'd better make sure you drop some torches on them.