I am not sure if enhanced (and force-fed) security features are the main problems here. Monopolies, spying and not having easily accessible alternatives (easy from the perspective of a more average user) are the main problems. Because google and apple are monopolies, most security critical apps like banking apps (that you unfortunately need now a days) don't support alternative OSs which also feedbacks the monopoly. Otherwise I am fine if some people opt for a phone that is basically a locked black box for them so long as there are other alternatives (including those which are still super secure/locked but does not spy).
It is much more crazy to me that you have to fight your device so that it does not sneakily do something that you don't want it to do (like install AI out of the blue or use data for mapping your habits). And most average users won't give this fight and that is what these companies really count on.