Most web design projects are scoped by a designer, built by a developer, and handed over with SEO as an afterthought, if it’s mentioned at all. The result looks sharp in a portfolio and ranks nowhere, because nobody thought about page speed, heading structure, or crawlability while it was being built.
A website has one job before anything else: to be found by the people looking for what you do. Design, speed, and search visibility have to be built together, not handled by three different people in three separate stages.
Retrofitting SEO onto a finished site is always more expensive than building it in from the start.