Why are Heart / Favorite, lists, Tracking, rating, different or missing on app vs web?

On IMDb phone app, when you view an Actor page, there’s a Heart button to add to pre-generated Favorite People list (requires having an acct).  And on a project page, there’s a Plus to add to Watchlist.

On IMDb web, I don’t see the actor Heart or Favorite People list (...you can create your own list); but it does have the Plus for project Watchlist.

On IMDbPro web, for either Actor or project, you can “Track,” and you can create own list.

… Why isn’t the Heart/FavoritePeople list on the web?  I’m guessing the built-in Heart & Plus improve a page’s rating.  Not sure it necessarily has the same boost when only added to a user-created list?  And on Pro, is Tracking utilized (toward rating?), since it’s separate from create-own-list?  If it's supposed to be same as Favorite, why give it a different name?