[corresation]

Even if they did, applying for a patent doesn't indicate that you have a valid patent, nor does it provide any protection whatsoever for patents that came before.

[Zikes]

The implication was that as part of the patent application process, one would normally seek out prior art.

[dublinben]

As others have pointed out in this thread, existing products already use this mechanism. It would be very difficult to patent something that was very obviously invented already.