I have been strictured at the J Pouch inlet for 10 or more years. It's very common to be strictured in that area due to inflammation from backsplash stool. My GI doc said as long as he can get a scope through the inlet, there is no need for dilation. He will only dilate me if he can't get the scope through. He told me dilation is risky because there is possible stretching, tearing and bleeding and he doesn't want to do it unless he has to do it.
It's way more dangerous to do in the anal sphincter area, because once you stretch the sphincter you weaken it and threaten continence integrity. It's been suggested to me when I had a skin tag in that area that you don't want anyone other than a colorectal surgeon doing any procedure that could weaken the anal sphincter muscle. I got that opinion from multiple doctors.
I don't understand your use of the term "tightening" things- with a stricture things are TOO tight and stool isn't passing through freely. It's the intestinal equivalent of a clogged pipe. You want a free flow, not a tightened flow. Your anal sphincter is the muscle that contracts and controls fecal continence, but once its stretched out, the muscle is weakened. It's not a question of tightness or looseness, it's a question of how strong or weak that muscle is after any dilation procedure.