- Putting important text inside of images
- Duplicate content out the wazoo
- Not making use of canonicals
- No sitemaps, html or xml
- Page performance issues
- Broken mobile support
And of course, poor content. You can't rank if you don't have content.
> Putting important text inside of images I'm sure the reason for this is that it's hard to parse text from images, and while Google could use their AI to figure it out, they don't bother. But it also prevents blind people from being able to read the text, so it does worsen the experience. > Duplicate content This makes the site harder to navigate for users as well. > Page performace issues Quite obviously makes the experience worse. > Broken mobile support. -..-
No site's output is 100% because of the tech team - content writers can put in weird code, marketers can add all sorts of stuff to say Tag manager, the robots.txt is likely from 2008. And a site built with code as the primary goal is likely lacking in some marketing oomph somewhere.
Someone who's job it is to find the right balance, and aim to maximise the returns from the single largest source of traffic, is pretty valuable.