> An inbox to receive mail seems good and valuable.

The only receiving mail applications that come to mind are bots registering for accounts. The point of verifying email is to prove you're not a bot.

> The point of verifying email is to prove you're not a bot.

I thougt it was primarily to verify that the address is actually yours, so they don’t unknowingly spam someone else and can reach you with important information such as pricing changes.

No, there's a separate way to gate that which is a captcha on the signup. If they pass the captcha that email gets sent whether it's really the right person's or not. Then if it's not, the account just never gets verified.