On desktop, I can create and edit the URL and name of a Top Site. On mobile, I can only pin sites that Firefox generates. The problem is, Firefox often generates Top Sites that are individual articles or entry pages (espn.com/nba/somearticle), whereas I’d much rather get index pages (espn.com), or in some cases an inner page (espn.com/nba). Creating a top site is also useful for cases where firefox doesn't realize a site is pin-worthy.