I'll say that it's less of an issue, 9 times out of 10, because what they're going to be good at is weathering repeated encounters.

There's so many monsters that do poison damage - especially in the mid levels - that you'd be hard pressed to run a campaign where they just stop showing up. Are you just not going to send anyone through the Underdark because a Monk is in the party? Stop using half the demons, aberrations, and magical beasts in the MM?

But for climatic fights, it can add to the drama when the encounter is on disadvantagous terms. Sometimes the cool shit is overcoming the seeming impossible.