It's literally the same architecture, ARM. That has nothing to do with voice chat. When you want to do multiple things (aka multiple applications i.e. running a game and a voice chat application) at once, you have to keep them in memory so that they can be run on the CPU. However, you have to manage how much memory is allotted to each program. This is a huge aspect of OS development, it's called multi-programming, and there is a huge amount of information on the subject over how to best enable multiple programs to run at once even when small amounts of physical memory are available. The biggest is virtual memory, but that's not the point. The fact that the Switch's pool of physical memory is an order of magnitude larger than that of the Xbox 360 or Vita (and the amount of memory reserved for the operating system, separate from the games that are being run) is sufficient to tell us that, no, Nintendo really doesn't care about voice chat.
I don't think you're going to listen to reason though, continue believing what you want to believe.