Why you need too many emails as long as you can enhance the security of your account through certain services such as 2FA or google authenticator.
Wallets do not need emails, so the platforms and financial services must be connected to secure emails and then use an offline phone to ensure that the e-mail is not compromised/hacked.
Creating a lot of e-mails requires the inclusion of a phone number which greatly weakens security.
Well, it's good to have an extra email addresses for when you're signing up for services or newsletters that aren't exchanges or work-related so your main inbox is kept as clean as possible and there's a minimal amount of spam in the main inbox you have where you're keeping things for exchanges and emails for other important sites. Ideally the email you're using for other signups doesn't have as much sensitive information on it, so you don't need as many security measures on that inbox.