Not every website needs a full rebuild.
Sometimes a few small updates are enough. A better headline, clearer contact button, stronger service text or updated images can make a useful difference.
But there is a point where small changes stop working.
If the structure is weak, the mobile version is poor, the content is thin, the design looks dated and the website does not support SEO or enquiries, patching the site becomes a waste of time.
At that stage, a rebuild is usually the cleaner move.