The short answer is yes, the long answer is not always.

The benefits of using your own custom domain, and the drawbacks of not using it, are listed below:

• Email providers would shut down, and all you have to do is changing MX records.
• You don’t always need to pay for extra addresses. A simple catch-all would solve the problem, and you can reduce spam by setting up rules with each recipient address.
• More solutions available. Some email hosting providers are exclusive for custom domain users, and you can engage with different providers with your inbound and outbound, get the best solution of each. For example, I self host my inbound email with mail-in-a-box and have full control over the spam filter, but I’m concerned with IP reputation and deliverablity, so for the SMTP service I simply choose Amazon SES at a low price.

The points above sound pretty valid, but people have raised some concerns:

Modern demands on email privacy are exceeding its original design and are still growing even more enormous. This is morbid.

Let’s take a look at some certain use case: Alice created a banking/finance account (something similar to Revolut/Paypal), and her login credential are listed below:

username: alice@example.org
password: You1-Should9-Use0-A7-Password4-Manager2!

Alice was careless, she didn’t follow the best practice of backup and lost her KeePass database (or her Vaultwarden database, or she forgot master password, or the paper that she wrote passwords on). Unfortunately, this is the only copy of the above username/password combination, there’s no way to retrieve.