A forum with 5 million people posting on it would be an absolute nightmare to be fair though.
They do a have a public Discord server which is active. Social (online) events are organised there, main one being a monthly drinking project where a certain style is typical chosen once per month and users will make an effort to checkin and discuss the ones they have, particularly if they are able to find rarer examples.
There are also regional channels as well as a dedicated beer trades channel. So yes, all of what you asked can and is done there, but to a lesser degree than here obviously - it’s no substitute for actual forums of course, it’s different, and for some things it’s worse since the conversation is always flowing around one topic, rather than separate threads for each thing. A dedicated discussion forum like this one is always going to be better than a chat server.
Also as Iznogud pointed out. Private messaging between users is a thing so trades can be organised that way although it’s not generally obvious if people are up for trading, better to go through Discord for that. People can and do use the lists feature in a similar way to how the wants/haves/cellar feature of RB used to be used. You can set all the details of the beers you have there (quantities, purchase date, best before date, canning/bottling date, vintage if applicable, as well as notes and a photo).