This is why I tell people to run high power, high fantasy, high magic games.If it's every time, it's absolutely the DM being adversarial to the players and just acting to give his creatures the counter to the players actions. The enemy wouldn't be able to do that anywhere near 100% of the time.
If it's sometimes, when it makes sense independent of player actions for the NPCs to have dispel or be able to set up an effective ambush, then it's not adversarial.
The setting where the PCs have all powerful unbeatable magic.....and the whole world has sharp sticks....it not a great setting. Sure the players love it "nahnah, nobody, even a God can break into our Tiny Hut! HAHAHAHAH!".
But also tons that can cast dispel magic....or worse.Why would a stone giant with no spells have dispel magic? There are tons of enemies that won't have or just plain can't cast it.
Why must a stone giant be a spellless target? How about a stone giant magic user of some sort? Maybe just a stone giant SpellSmasher!