What you're referring to is called "pressing", and there's a very split opinion in comic collecting regarding whether or not it should be considered a form of restoration. There are services that do comic pressing with heat and really chonky machines that can turn a "very fine" book into a "near mint" book, potentially raising its value by a significant factor.
Honestly, a more apt comparison might be replacing staples. Staples get rusty, and that can leech into a book and damage it further, so some folks remove the staples. I have seen people that then keep those original staples in a baggy with that particular book, but some folks just replace them outright. I have even heard of people going so far as to acquire period accurate staples for replacement. It gets a little crazy, but there are people who only want completely original collectibles, even if that means the collectible is in less than ideal condition. It's not for me, but I say, to each their own.