Like a few other commenters, I had never even thought that taking your phone into the shower was a thing until I saw this post.
Just... why? Why risk it? Your average smart phone is anywhere from $500 to over $1000, so what's so important that you're deliberately exposing it to water and the risk of dropping it (especially if you're using shampoo, conditioner, soap or any other bathroom product designed to act as a cleaning agent)? Surely whatever it is can wait however long it is you're showering for?
Personally, I wouldn't want a friend/relative/whatever phoning me or answering the phone if they were in the shower or using the bathroom.
I can understand one of the other comments about using it to listen to podcasts/music/videos/etc., and at least in that case the phone is presumably far enough away (and not being regularly accessed) that it's at lower risk. Fair enough -- I sometimes do that whilst washing dishes. Still, I think I'd struggle trying to listen to something whilst actively showering -- too much other noise.