That assumes you have that email account on your phone. Also that you have your phone with you, that your phone has signal / wifi, there's no delays, no greylisting, no spam filtering that might catch the email, ...
There's just too many simple ways it can break down for it to be a good system.
Okay, but what if you don't know your password and your password manager is offline or you don't have access to it on your phone or the phone ran out of battery or... I assure you we can find a similar amount of cases where passwords would fail. It's mostly novelty phobia.
We're used to one way of working and have our setups for that. We don't want something different but not because it's worse. It's just different.
And even more, when you have a problem with your password, what do you have to do, yes, email for the most part.
That assumes you have that email account on your phone. Also that you have your phone with you, that your phone has signal / wifi, there's no delays, no greylisting, no spam filtering that might catch the email, ...
There's just too many simple ways it can break down for it to be a good system.