Why a shingle repair extends past the damaged spot
A replacement shingle needs the right size, exposure and fastening for the surrounding covering. Its upper edge must sit beneath the course above so water continues downhill over the laps. For flashing work, nearby shingles may have to come off to restore that water-shedding connection.
That can make a sound repair larger than the damaged part you can see. Color matching has limits too: weathered shingles may no longer match a new product, even when the nominal color is the same. Those appearance and scope limits should be explained before work begins.
If the adjoining roof cannot support a lasting repair, the replacement option needs a clear explanation of what has failed and how much roofing must be renewed.