This is only true if you're working with multiple completely separate teams each working in a silo to develop their own product and then post hoc some manager decides they have to have the same feature set. If they do it the right way around, specifying the common feature set comes first and then the dev teams do the app architecture on their separate platforms. As the features are developed and change requests inevitably arrive, the same sequence applies and you have an orderly process and the same app on two or more platforms without having to graft a third party dependency octopus onto your codebase.