Sending, receiving, and organizing email in Outlook.com
Microsoft is not the only one mandating this, a lot of email service providers are now mandating this.
It will be ONLY relevant to you if you have your own custom domain email address, you need to then configure these records to make sure your emails sent to outlook.com/hotmail.com users won't be rejected by Microsoft.
However if you are using outlook.com/hotmail.com address yourself, and you are not receiving some of the business emails, then it is on THEIR end that they need to make sure these records are set up correctly.