A two mana rock than can grant trample and card draw when you dont need the mana is very, very good, and helps keep games moving
Card not found doesnt really see play, but I bet it could be great in certain environments (like slow formats, where graveyard hate isnt played much)
I could write an entire article just containing scenarios that prove Narset Transcendents power level, but this is one of the criticisms that wasnt just about that
However, there are some key things that instants usually can't provide
The Legend Rule would change a few more times over the years, eventually shifting from a creature type to a supertype, like basic on lands
Currently, not all sets on Arena have voucher codes