I don't know, so please correct me if I'm wrong. But isn't DNS record creation now handled automatically, and in the background, with the standard one-stop-shop site systems like Wix, Weebly, and SquareSpace?
If so, and they decided to further support integration with senders like MailChimp by auto-creating subdomains as needed, and it worked perfectly, that would make it all easier. But anything less than perfect, and users (ie small business owners) would be hopelessly lost.
If the one-stop-shop handles your domain registration, then yes.
Regardless, whoever handles the registration should have an interface to add records. For example, you'll need to add MX records to use Google or Office365 for your mail service. You'd also need to add TXT/CNAME records to prove ownership of the domain for Google Webmaster Tools, etc.
If so, and they decided to further support integration with senders like MailChimp by auto-creating subdomains as needed, and it worked perfectly, that would make it all easier. But anything less than perfect, and users (ie small business owners) would be hopelessly lost.