Why is there not a link here to the information about how to forward messages from an iPhone to a Mac?
The information on the support page for "can't receive messages on my Mac" ought to have a link to a support article (I found a LifeWire article that explains the situation nicely at https://www.lifewire.com/how-to-get-text-messages-on-mac-4685314) explaining about forwarding SMS messages from iPhone to Macs.
That is, I searched and found the article for not being able to send/receive any messages at all, but what I wanted was to be able to receive/reply to SMS messages from my iPhone from my Mac.
The user-interface for that (iPhone Settings -> Messages -> Text Message Forwarding -> allow other devices) is very much not obvious. Otherwise, sitting at my Mac, it's a mystery why it doesn't "see" those messages.
iPhone 13 Pro Max