What I really can't recommend enough is paredit. It ensures balanced parens by always creating a close to an open. Typing a close just jumps you past the nearest close after the cursor. Along with the thing where the cursor momentarily jumps to the open paren when going past a close paren.
When I need to add another expression to a scope, I just hit close paren until I see the jump to the relevant open paren then hit enter.
I do know some older(than me) Lisp programmers who even find paredit excessive though.
Eventually, I found that when reading lisp I almost never actually look at the parens at all, only the indentation.
So probably parinfer is solving a problem that most Lisp programmers aren't looking to solve. That would be my guess anyway.
All this is not to pass judgement on your for finding it helpful, and I certainly agree that having more tools for beginners to get used to editing S-expressions is helpful.
It mainly helps adoption, so in a way you are right, it’s not a problem for current users… but it is a problem for industry (as much as I deplore the reality that such a superficial familiarity bump detracts so many people).
That, or I have a plugin running in the background for years without me noticing.