DANE is a kludge that should be put to bed, not promoted as a solution to a problem which shouldn't exist.

STARTTLS exists for two reasons (https://www.fastmail.com/help/technical/ssltlsstarttls.html):

1. Wanting to accept mail insecurely.

2. Not wanting to use two different TCP port numbers to send and transfer mail.

To solve these problems they created STARTTLS. But obviously, STARTTLS isn't actually secure (even though that was the point of supporting TLS). So to make it secure, it's suggested to use DANE - a standard built on a different procotol, requiring a feature that is controversial, potentially dangerous, and not widely implemented. So you can use a kludge (STARTTLS) with a kludge (DANE) to send and transfer mail securely. But should you?

Since 2018, RFC8314 says that e-mail submission should use implicit TLS, not STARTTLS (https://datatracker.ietf.org/doc/html/rfc8314#section-3). Therefore the use of STARTTLS, and the use of DANE to make it secure, are deprecated. So while you shouldn't use DANE for anything seriously, you really shouldn't use it for SMTP.