why not add popup description to setting label?

Hi,

You can click on the "help" button at the top of the page. There, you'll find the description for each option of that page.
As it opens as an inline iframe, it should be easy to look at the options and the corresponding help at the same time.
What you're talking about, tooltips, is great, but you can't have long description in it, or images, or links to other docuemntation pages for further reading, etc. So they are quite limited.
Having the documentation like we did allow for more leeway on how we present the documentation of the options.