[miloignis]

Strong disagree - defense in depth is a thing.

I once had my phone, which I had turned off, loudly ring during a moment of silence I was attending. It was extremely embarrassing, and until I replaced that phone whenever I was in a similar situation where it was critical to be quiet, I removed the battery. It wasn't that I didn't trust the phone or it's software, but mistakes and accidents happen, and for some critical situations it's better to be safe than sorry.

Same thing applies to phones with hardware switches.