iPhone microphone glitch

During vacation in Florida, my old new (will explain later) iPhone 4 become muted when making phone calls. Neither the regular microphone at the bottom of the phone nor the mic for the speaker on the top worked. Except for making phone calls, Skype, VOIP phone app, etc. worked fine for both microphones. I made an appointment at the local Apple store and the "Genius" there told me that it has to be replaced. Since the 90 day warranty (I recently paid $170 + tax to have it replaced due to a real hardware issue) just expired 3 days ago, I have to pay another $170 for a new iPhone 4.

At the same time, he did mention that this could be a software issue as the voice memo is working fine. Well the only way he suggested to clear that is to restore the iPhone as a new phone, which didn't help after spending quite a bit of time to resetting the phone and restoring it.

Luckily I brought my new Blackberry Z10 with me, so I did have a phone to use during vacation.  Once I got back home, a more thorough Google search turned up this post from MacRumors.  It referred to this blog post stating that this is a software glitch which disables the microphone for the native phone call App in iOS. The solution is to play the iPod app (or Music app in iOS 7).  Initially, this solution didn't work. However, I do have the impression that this problem happened when I was using the Microsoft Sync via Bluetooth on the rental car.

After connecting to my Bluetooth headset and playing music for a second then disconnecting it, the problem was solved.

What's surprising is that this seems to be a rather common problem based on the feedback/comments on the blog dated back to 2011.  Why on the world didn't Apple solve the problem or, even recognize it by the "Genius"?