SASL auth and TLS are fairly common nowadays, threaded discussion is not really mandatory for a good modern chat (Telegram, Discord for example don't have anything like that,) image unfurling can be done by the client, and there is actually formatting and some clients will autoconvert basic markdown to it for you.
IrcCloud is an example of a client that tries to solve pretty much all the issues and you can even plug it into a desktop IRC client and get most of the functionality including history. It's not necessarily better than modern chat or anything, but I love having a modern chat experience while being able to discuss things with people and groups who virtually only use IRC.
If you aren't a fan of hosted services you can run your own BNC. Some IRC servers have built in BNC services that give you things like better security and channel history.
Let me reaffirm that I am not of the position that IRC is perfect or modern. But you are misrepresenting it a fair bit, even in 2006 I was connecting with TLS (sometimes self signed certs though.)
IrcCloud is an example of a client that tries to solve pretty much all the issues and you can even plug it into a desktop IRC client and get most of the functionality including history. It's not necessarily better than modern chat or anything, but I love having a modern chat experience while being able to discuss things with people and groups who virtually only use IRC.
If you aren't a fan of hosted services you can run your own BNC. Some IRC servers have built in BNC services that give you things like better security and channel history.
Let me reaffirm that I am not of the position that IRC is perfect or modern. But you are misrepresenting it a fair bit, even in 2006 I was connecting with TLS (sometimes self signed certs though.)