Right on Commander !
Actually only ships of up to 3 ranks below, equal to and above your current rank count towards progression with proportional effect. So no you can't achieve Elite by just killing Harmless Side winders.
But you can from shooting scouts that are one of the easiest targets in the game. It's still a reflection of grind as opposed to having much to do with combat skill. My point still stands.
This does imply a broader issue with ED and Frontier's seeming inability and/or reluctance to make any game mechanic about something other than time sink and grind....but that's perhaps a conversation for another thread.