Having the update tied to fps would also make the game less smooth when a player has lower fps.
Yes that's what I mean, when you're calling the delta time from one frame to another and using that to only update the game (not render) 60 times / second, wouldn't that hinder performance? Or am I missing something.
I am confused on what you are trying to say.
Are you saying updating the game every frame is a performance hit? Of course it is, but it also can't be helped, unless you your game never changes, at that point, it is just a single image.
If you are trying to say you want to reduce the update rate from 60 updates per second to 10 updates per second because you are using delta time, that is possible, but your game will feel not feel very responsive unless you make another update like function that processes user input / menu control / what ever else, and only let the game logic be updated at 10 updates per second (may be acceptable for a turn based game).
My quote was more towards not using delta time. Also remember, you need smarter collision detection when you are using delta time, if my character moves at 10 meters a second, and for some reason my game freezes for 10 seconds, the delta time would then mean my character moved 100 meters in the update, if you are doing collision by checking to see if your hitbox is inside of another hitbox, I would teleport over all objects that are less then 100 meters away.
So having a lower delta time for the above situation would increase the accuracy of the collision detection. So forcing 60 updates per second would ensure that the collision detection is always accurate to that precision.