It's good to see a new tool to help learn about Themes.

Themes lack the coverage & support that we expect with plugins ... yet the theme is more-fundamental and is unique, with each site. Logically, each theme offered in the WordPress collection should have more & better documentation than a plugin. Yet the opposite is true.

Raising interest & awareness of the theme, as WhatTheme and related tools do, is all to the good in moving toward improved treatment of theme resources.

(That some of these tools also detect plugins, is excellent.)