Are you suggesting that getting hearing aids preserves your hearing or simply that people with advanced hearing loss benefit less from them?
Imagine if you stopped playing basketball because of a bad knee.
Then years later you get a knee brace and are able to play again.
How long, and how much practice would you need before you could play at the level you were at before the knee problem?
And without properly fixing the problem (just using a mobility aid) could you ever return to pre-knee problem levels?