I will admit the current Verizon and AT&T wireless squabble over one network being able to handle a voice conversation while at the same time allowing you to use the internet, does have some legitimate uses.
1) After seeing the commercial, I hadn't realized that this was a limitation of my phone, so I then tried it. It turns out, that if I disconnect from WiFi, thus does indeed happen. But I did need to be on my headset for me to still be able to talk, which I am not very often connected to.
2) While using the GPS navigation, which requires internet, I suppose a call could come through in which I would be required to interrupt a data navigation session to take the voice call. True, again another case. However, I don't drive, but when I do, its for a two hour inter-city commute that I know all too well, that the GPS is more for a driving companion, that the voice call would replace.
Final note, the flagship device of the accusing network can not actually multi-task, so although the network can do it, the device is not going to allow you to background a call to tweet your grandmother that you'll be joining her for butterscotch candies and a game of bridge. I mean how rude would it be not pay attention to Grandma's tweet because you were too busy talking on the phone?