Funny, that this post has a bunch of links, and no single link to actually the subject of this post - WordPress Themes Directory.
Here you are: https://wordpress.org/themes/

Also, the problem that is not covered in the post at all.
To be able to fav the theme you need to be logged in (obviously), but the theme directory doesn't show whether you are logged in or not, and it doesn't have a form to log in. So you just stuck in no ability to fav. Very bad UX.
Hint: go to plugins directory, log in there, and come back to theme dir. That's a crap.