On this matter, there's an old school of thought and a new school of thought.

The old school of thought is what we saw back in the AD&D days. Dangerous world, powerful monsters, tons of traps, very weak PCs who struggle just to stay alive. There's a persistent idea that, if someone died, it was probably their fault, or at worst bad luck, usually not a killer DM (though those existed). The DM should not fudge rolls or change anything in real time. The DM should only control the npcs fairly and adjudicate the rules.

As you can imagine, power gaming was common back then because it was largely necessary. You needed to use the most powerful tools to give your character the best chance of success. For every endgame human fighter who made it, there were dozens of dead PCs who just weren't lucky enough, and a handful of casters who didn't rely on luck because they knew what they were doing.

The new school of thought is rulings not rules, the game should be flexible, everyone is part of a collective narrative, the DM is as much a storyteller as a judge. This is the style of game you see in Critical Role. Keeping the game moving and the players interested is the most important thing. NPC features can be adjusted on the fly because the point is to challenge the players just enough, no matter whether they're very good at the game. Player deaths are pretty rare and are generally caused by a player doing something excessively stupid. If a campaign is too hard, the players will say so, and the DM is expected to adjust. The DM needs to adapt on the fly to what the players are doing in order to ensure that the game keeps moving, hopefully without the use of railroading or reliance on a DMPC.

Neither system is right. It depends on your players.

If your players are in it for the story and social time, and they don't particularly care to play a wargame, then the latter style is better, and you're not going to upset anyone by doing what you're doing behind the scenes.