Don’t Prevent Embedded File caching
If you prevent JS, CSS and image caching, such as a nocache header tag, Google will need to keep requesting the files for rendering, which may slow down crawling of the site.
Fetch & Render Shows Results for a Googlebot and Browser User Agent
The Fetch and Render tool shows you 2 different renders, one for Googlebot which used the Googlebot user agent, and one for users which used a browser user agent. If JS/CSS is disallowed for Googlebot, it may not be able to render all the content in the same way.
CSS and JS Crawling Is Important for Mobile Compatability
Disallowed CSS/JS Is a Problem If It Prevents Rendering
Disallowed CSS and JS is only an issue if it actually prevents Google from finding visible content, or rendering pages correctly. Other JS files don’t matter so much. There aren’t any penalties or anything like that.
Text Position on Page Doesn’t Matter for Relevancy Matching
Moving text to the start of HTML, then moving with CSS would be pointless. Keyword density isn’t relevant, write naturally.