Simply put, what you heard elsewhere is incorrect. The tool tip for the Scout Mastery reads as follows-
Wards gain 25% increased vision range for the first 5 seconds after placing them.
Riot is fairly straight forward when it comes to Runes and Mastery's and as such the tool tip would specifically say it affected champion abilities and summoner spells as well.
It is possible that for a time this was the case, but it would have been fixed very early ononce it was brought to RIOT's attention.