Blocks are not yet mature at all and for maintainability is more easy to have the template as code and not from stuff in the DB that require parsing and involves more performance.

Also, we are talking to build a website, usually they don’t change so much so all this customization is not needed when you have an agency that do the template to you. It is needed when you don’t have someone for you that is the Wix/Shopify user target.

If you are using WP is to do a website that align at best what you need.