If I understand you rightly the term is used to differentiate the games in which there is a single, linear path of level advancement over time, and the games in which you can go to any 'level' you want to, and do them in whatever order your good enough to do them in, provided you have some basic items, (in SoTN's case, the cube of zoe, jewel of opening, and others).
Wouldn't Simon's Quest be a metroidvania? You are technically able to run around and do the levels in any order you want.