Earlier quoted context omitted.
At least your friends don't need a whole lot of instruction to join. Inserting pictures is pretty easy. And it's mobile.
I remember IRC in the late 90s, early 2000s having A LOT (like 9 out of 10) of people who otherwise had no idea about computers (remember droves of people disconnecting after 'Press Alt+F4 to get @'?). People who didn't knew the difference between a file and a directory (or folder) were on IRC with channels having hundreds of people. If someone can figure out Facebook (and trust me, Facebook is far from intuitive for…
Yeah you can set up some always-connected relay on a server and bounce your client through it to still get the conversation backlog when you weren't online, but it's not reasonable to expect an average computer user even have an always-connected machine to run it on, let alone actually get a relay working.
If they can use Facebook they could use IRCCloud, but that's $5/month and Messenger/WhatsApp/Discord/Slack are free.