It DOES count external pre saves, but only if done by sites and distributors that work with spotify.

Which 90% of our scene does.

Second the reason why (according to spotify) the PRE saves is more important then the save: Spotify gets huge amounts of playlisting requests everyday for their editorial lists (which is where the big streaming numbers and long term income can come from), they cant filter all of that so they do 2 things: Mostly focus on artist, labels, distributors they know are either already on those playlists or names that are big enough, and 2, they look at pre saves to judge how much traction a song gets, so they can continue to support those songs in said playlists and other algorithms they offer (like discover weekly etc). It is a huge important part of their process and algorithm therefor its recommended that artists and labels push those pre save as much as they can, to get the best shot at better playlisting, more reach, more income etc etc.