I disagree. The vast majority of emails I get don't trigger a notification, as I get over a hundred non-spam emails a day. These are high priority things, so that notification coming in through a higher priority notification process makes sense.

Email isn’t instant. It is usually delayed by 30-40s, but quite often gets into the 20-30 minutes range. Hell, a few weeks ago it took 6 hours to get the login verification emails for my epic games account and couldn’t login.

Emails don’t bounce until they haven’t been able to be delivered for DAYs. With an “s,” so you won’t even know there is a delay until the message doesn’t even matter anymore.

I don't want to be online on my phone, except when I decide that I want to browse the Web because I have spare time or need some information. SMS is perfect when I want someone to reach me in a timely manner.

Well, luckily I live in country where SMS spam is not an issue. If I look at the inbox of our IoT-like devices in the US, my approach to communication might be less feasible.