Falsehoods people believe about email
Not everyone has an email.
Once a businesswoman has proudly shown me a dumbphone and told me that she does not have a personal email, only a corporate one. That persuaded me for a while, until I learned that her husband was prosecuted for money laundering around the same time. So yes, not everyone has email, but those who don't a few and have very good reasons.
Email is unsecure
Aside from spam and automated emails, pretty much all email typed interactively in an email client is encrypted between the sender and the receiver.
We could have a long technical discussion here about the opportunistic encryption of STARTTLS or about the market share of Google, Microsoft and Apple, but the reality is that is is encrypted for all practical purposes that matter to ordinary people.
You can impersonate anyone in an email
Long gone are the days when you could send a mail from gates@microsoft.com from your personal computer. To start with, port 25 is probably blocked for sending at your ISP. Then, even if you managed to send an email, it will be probably rejected as coming from a residential range of IP addresses. But even if you send a mail from Amazon SES, then the receiving SMTP server will use SPF and DMARC to check if Amazon SES can send emails on behalf of @microsoft.com and it won't.