I'm not a fan of the way some NPCs get inflated stats and hit points.

If they are supposed to be stronger, increase their level, but follow the same rules for whatever class they happen to be in.

Take the githyanki, for example. Someone just dumped extra hit points on them.

Nere's stats are ridiculous.

Or look at the goblin boss in the first fight outside the grove. I'm pretty sure he's level three and has a proficiency bonus of +3. Why?

The druids in the grove turn into bears with 19 hit points? Why? That's not the same as the player character druid.

I think consistency is important. It's also important to, for lack of a better phrase, play fair. I don't trust people who think the rules apply differently.