This works two ways though. You can do the same to them as what they can do to you. When I DM sessions the players want to do things like throw a jar of oil into a pit then set it alight to kill the monsters in said pit. And I let them because its innovative thinking.
I abuse the shit out of the push function to make combats easier. But at one point a clacker did the same to me. Pushed a character of my party over a cliff and one shotted her. It was awesome, and now I think more carefully where I place my characters.
The same goes for surfaces. I make sure I am not vulnerable by planning where I go and what I do. At the same time doing things like throwing explosive objects to create area effects.
Its not really that easy.
NPCs can just unload their whole arsenal onto you, but D&D is designed around limiting the players ressources and making every spell count, especially at lower levels. Sure, in BG3 you can just long rest everywhere at any time with no penalty, you can literally take a long rest 5 feet away from triggering an enemy encounter and nothing happens, but is that really how you want to play a D&D game? Long rest after every fight because you have to blow every single spellslot each fight to be on equal ground with the enemy throwing Fire and Acid at you? That kinda beats the point of playing a D&D game in the first place and we can just go back and say "lets just make it DOS3, give spells cooldown and remove spellslots".
There is a reason the Monster manual doesnt give each goblin a bottle of alchemist fire in D&D.
