I once spammed text messages to the person whose phone number was mobile prefix + 1111111. I didn't realize until he called customer service to complain.
This will happen even more when Android 13 is released. There is an extra permission for having notifications shown for every app separately. I know for sure I will disable notifications for pretty much every app except email and messengers.
There are alao plenty of us who just have notifications set to vibration mode without any sound full-time. The only phone alert in my case that makes sound is the alarm. Unless i put my phone on some hard surface or literally next to the bed, there is no way i will hear vibrating notifications, even when awake.
In general, I found vibration-only to be pretty much the default for a lot of people I know (though I am sharply aware that this is just anecdata and doesn't say much about the real state of things). I tried googling whether there was some breakdown of notification vibration vs sound smartphone users, but, sadly, couldn't find much.