For the most part I agree. But I think this is unfair to the DM and is what makes taking on the role of DM so intimidating to many. Perhaps I'm mentally inadequate, but I just am not going to remember the details of all the feats and spells. I don't think that it is too much for me to expect a player to know how their spells work. But even for simple things like a fighter attacking someone with a sword, it is easier for the player to look at his or her character sheet than for me to talk through attack and damage bonuses. As a DM, I already have to prepare for all the NPCs they may encounter. I invest a lot of time and money on physical and digital aids to avoid slowing down the game to much.
I suppose I could just have all the character sheets in front of me and roll the dice for the players as well. This may work when using VTT tools like Fantasy Grounds, but I run an in-person game and my players like to roll dice. I also find it more engaging when players roll their own dice.
If I have to do all the work, well, that would tip the balance for me and it would just be work. Players at my game need to pull their weight to help make the game run and make the game fun.
From what I've read in similar threads, I think I tend to be far more accommodating and patient than many DMs, but at some point, lack of preparedness is rude and life is too short to accommodate rude people during my downtime.