I imagine if attacking midfield, cutting-in-from-the-left were a position that England were lacking in then Ramsey probably would have got a call-up. But last season the likes Rashford, Grealish and Foden were doing just fine.
Likewise, if we had a young player who was excelling in a position where England's current choices are Jordan Henderson and Kalvin Phillips he might have been called up just like Mainoo has been.