Ask your mother if she's heard of Variable Valve Timing or the equivalent for her brand of car OR ask her if she knows Linux or... for that matter ask yourself if you know the OS on Nokia 3310? Most mothers don't even know what a OS is.
Edit: The OS is called "Series 40".
iPhone was ground zero for the general public consciousness in this space, it made this product category mainstream. It's silly to argue otherwise.
Also variable valve timing was plastered on trunks of cars in the 80s so folks of a certain age should recognize the term, and Linux as a term seems pervasive enough that most people should at least have heard of it; they likely have no idea what those terms actually mean though.
Not to mention developers were never going to create apps for the platform.
definitely wasn't an improvement