The whole smartphone issue is a bunch of nonsense. Those same people have computers with internet access. A smartphone or computer can be used constructively or abused. The same can be said about anything. Maybe people should poke their eyes out to avoid seeing anything improper?
Some Bochur once wrote about a girl not being tznius because she wore a seatbelt. Things just get so absurd. Look at the entire person and see if she is right for you. The smartphone is a non-issue proposed by maniacs, like this supposed Rov in Bnai Brak holding exorcisms for smartphones. You posted here, so you have a computer with internet access. Why is a smartphone worse than your computer?