We are talking Middle Earth, not Hogwarts.
Most of middle earth does not possess magic, of those that do, most of it is not that kind of magic.
The only persons in middle earth that possess magic in that magnitude are not of middle earth, they are Miar or Quenya.
Gandalf, Radagast, Saruman, Sauron, Melkor,the Blue etc they are not human dwarvish or elvish nor are they of middle earth, nor are they existent in large numbers.
Sauron is here through following Melkor, no those two would not like anyone challenging their power, even Eru who could break the rules and bitch slap them
through the door of night if that was his way.
They ploy magic by main force, but that is not the norm, they are the exception.
Saruman forgets his place and becomes full of himself and dabbles a bit with it
but never makes it to full retard.
Gandalf and Radagast never use it to influence the world and aside from parlor tricks
make minimal use of it, they are even forbidden to match power for power with the corrupt Maiar.
So magic has little influence on the day to day life of middle earth.
No magic brooms or fireplaces, no spells to fix broken things and clear up messes.
And no all powerful wizards to keep everyone under boot heal.
Even Sauron must resort to raising physical armies and fighting through physical means because even his magic power has sever limits.
he can not rule middle earth using magic only by main force.
Nothing is prevented from happening due to magic.
If anything modern advances in technology don’t exist simply due to lack of need.
The people don’t perceive a need.
They are happy to plow their fields by hand, catch fish by hand etc.
Perhaps even take great pride in it.
They are perhaps a bit unrealistic as modern people go, but it is a story after all.
And it is not like it is without precedent, there have been real times and places where
the people remained mostly the same for a very long time, simply because they were happy as they were and did not feel any drive to make any great changes.
One other very important thing.
Most important thing actually.
The reader does NOT want the world to go making drastic changes.
The reader does not want middle earth to morph into a 1970 global industrial complex
That is not the story they came to read and so it is not the story Tolkien has written.