I wonder if it's kinda a stockholm syndrome or if it caters to one's ego somehow. After discovering a feature, one feels smarter / more connected to the device, compared to if it was actually easier to use from the get go.
For example, he texts frequently but doesn't know how to check his email. Because I am the tech support child, he reaches out to me for iPhone help. However, since I am not an iPhone user, I always struggle and sometimes fail to solve his problem.
Perhaps this is a sign I have not dedicated enough time to learning this new OS in my family ecosystem, but I do feel it is the least-similar to the other OS's I have used. It's like if my dad was learning programming and asked if I'd help him with his Lisp program. No thanks.
Though maybe I am just a luddite and the universe is written in iOS.
Not just unfamiliar, difficult.
Sure, discoverability is good to have, but it is not a failure that you need to be told about it as long as it only contains features useful to power users.
Requiring experts to undergo some training to make the most out of their devices is acceptable UI if the final interactions are optimized for their use; double so if it doesn't interfere with usage by untrained users.