Definitely not overrated. If it were, there would be no FS places. After all, a HJ is half the price and safer.
If you are purely talking physical stimulation, the HJ may provide more of that. I would posit that if you drilled a hole in a wall so you couldn’t see or hear the woman and put your member through, the HJ would probably be more stimulating than intercourse (especially intercourse with a bag).
With intercourse, the stimulation is a combination of physical and mental. Its not only the physical sensation, It’s seeing you slide inside of her. It’s hearing her moan. It’s you body in contact with hers.
Of course, as others have said, because it is largely psychological, it’s going to be best when it’s with someone who is legitimately into you are you are into them.
This is where the hobby can get dangerous. One in a while you will find that with a provider and have a mind blowing experience. Then you end up “chasing the dragon” trying to get that experience again.