How do you feel about players being countered? Barbarians especially.

I have witnessed and been in conversations around the topic of players being countered.

On one hand, it could be considered a facet of challenging the players alongside knowing when/where to fight, when to use resources/consumables, and where to apply a character's strengths. It could also be part of spicing up combat.

However, the game itself doesn't seem to make weaknesses particularly engaging, or at least, not all weaknesses/counters are made equal. And for that, I'm opposed to the idea of countering, or at least, certain counters.

Barbarian, for example, has very little to interact with its weaknesses such as flying enemies, making mental saves, and recovering-from failed mental saves or playing around them. For barbarian, getting frightened has little to no decision making and can even be perceived as an attack on the flavour of being a fierce fearless warrior.

For full casters however, facing a "counter" in the form of a magic resistant and legendary resistant enemy has plenty of decisions. There are anti-magic fields, but the ways I have seen them used are more about positioning rather than creating a situation with absolutely no options.

How do you feel about it?