I take it, that you've never had to work with html emails then? groans You lucky soul!
My first website in '96 had a repeatable background image with text over the top. That's still problematic in email templates and easiest to avoid.
https://templates.mailchimp.com/getting-started/html-email-b...
Building these types of emails without tables is doable, but you are going to get a lot of inconsistency depending on the device/client/browser.
It "worked" in Outlook (2003, 2007, 2010), Yahoo, Hotmail, and Gmail. And had to display correctly to the recipient in each of those clients.
It was by far the biggest pain in the ass I've ever worked on. Tables weren't enough to make it work outright. Outlook 2007+ couldn't do background images on a table cell, gmail would collapse empty cells, hotmail would remove certain inline styles, and yahoo was actually pretty nice.
The company I worked for took the project on for an equity split + payment plan, we saw a few hundred dollars from it before they went out of business.