Why rebuild instead of patching
Many small business sites are built on themes and plugins stacked over years. Each one adds code that every visitor has to download. Patching can help a little, but a rebuild removes the weight at the source.
A rebuild is also a chance to fix the things that quietly cost you customers: a phone number that is hard to tap, a contact form that goes to an old email, or service pages that do not answer the questions people actually ask.