A service history is not only useful for a sales listing. It is an everyday tool that helps the owner understand what has been done to the car, when it was done and what may need attention again soon.
If your records are in order, you do not need to wonder when the oil was last changed, at what mileage the brakes were done or when the battery was installed. That helps avoid duplicate spending, late maintenance and annoying surprises.
When it is time to sell, documented history gives the buyer much more confidence. If dates, mileage, workshop names and completed work are clearly recorded, the car appears more trustworthy and transparent.
There is also a practical benefit when ownership changes. The next owner can immediately see the state of the car instead of starting from scratch.