How people perceive a page is a big indicator of the quality of the page.
Is there truth to that observation? A low quality page with a smart web design, great use of fonts and graphics and an easy to scan layout can be perceived to be a high quality web page. The opposite can be perceived as a low quality web page, even though the content might be original, high quality and useful. How a web page is perceived owes a lot to superficial factors outside of actual quality.
If it's enough for the web page to be perceived as quality, with the result that a Google user is satisfied, then the result is that the factors determining what will rank relate to perceived user satisfaction, not quality. Every metric listed, including conversion score, does not necessarily relate to quality or actual satisfaction for the user.
Every metric quoted above does not necessarily indicate the quality of the page. It only indicates how well the web page was engineered to motivate a site visitor toward a specific action, in addition to other superficial factors outside of actual quality.