Why is email needed for account creation and verification?

Because every other option has a fatal flaw.

Username? Not unique across platforms. Phone number? Not universal (costs money, excludes people, changes carriers). Social login? Ties your identity to a company that can ban you tomorrow. Email is the only identifier that's universal (everyone who's online has one), unique (no two people share the same address), and verifiable (you can prove you control it by clicking a link).

So when When you create an account, the service needs to confirm two things: first, that you're a human (not a bot mass-creating accounts), and second, that you actually control that email address (not a typo like "gmial.com" or someone else's address entered by mistake). The confirmation email does both. It proves you have access to that inbox, which means password reset emails will reach you, and it filters out fake signups before they pollute the database.

This matters more than it sounds. A database full of bad addresses kills your sender reputation. When half your signups are typos and you try to send a welcome series, you get bounces. Postmark and other transactional ESPs will suspend your account if your bounce rate spikes. The confirmation email is your first line of defense. It's the moment where a casual signup becomes a real relationship with real deliverability consequences.

Some services try to skip email verification (just ask for a username, send a text code, or trust a social login). That works for casual apps, but it breaks down for anything where account recovery matters. If you forget your password and there's no verified email on file, you're locked out forever. Email isn't just for verification, it's for password resets, security alerts, and any message that needs to reach you when you're not actively using the service. No other channel can do all of that reliably.

And if you're building account creation flows, make the confirmation email fast and frictionless (nobody wants to wait five minutes for a code). Use a transactional ESP with good deliverability, write a subject line that passes spam filters ("Confirm your email" works, "VERIFY NOW!!!" doesn't), and link directly to the confirmation action (don't make people copy-paste a code unless you have to). The easier you make it, the more people complete it, and the cleaner your list stays from day one.