The literal definition of “restoration” doesn’t matter. The context and intention are the important parts.
Restoration of a car is a form of maintenance. You can’t keep a car functional and in untouched condition so restoration is necessarily a part of the maintaining vintage cars. Likewise, as @smpratte said, paintings are 1/1 and also are often centuries old. They are restored to enjoy the art the way the artist originally intended. Additionally art restoration is an art itself, where everything you do is to maintain the original integrity of the piece by making as minimal a change as possible and to ensure all your alterations are completely reversible.
There are also plenty of hobbies where restoration harms value. Coins and stamps consider polishing or cleaning an undesirable trait. Diecast cars and antique furniture too. The thing these all have in common is they are mass produced items. The value is in finding an unaltered item that is still in amazing condition. The reason we value condition at all is because we all partake in the battle against entropy and finding that item that has beat the odds and still looks new years and years after it was produced. To produce a facade of that is entirely counter to the point of valuing condition in the first place.
If the distinction is still unclear, let me fix that. A person with a restored car knows exactly what parts are original and which ones are new. An art conservator documents all their changes and makes a lot of them visible under UV light. A successful pokemon card “restoration” tricks PSA into giving a damaged card a higher grade in order to unknowingly pass it to the next person at a higher price. These aren’t the same things. Again, it comes down to context and intention.