I'm sorry, but that is incorrect. I just tested it on my LG G2. I turned WiFi completely off, called my other phone and then proceeded to browse the internet during the call on 4G. If you'd like I can take a video for you.
Edit: After doing some research, it appears that this is a limitation on the iPhone and not on the Verizon network. The newer phones on both Verizon and Sprint can do calls + data at the same time.