I'd have to agree on some point with people about what platform to use. The community will decide for itself what it wants to use. I use IRC all the time, it's cool. But there is an issue where it's an old technology, and more people with favor over the easier to use software. Discord provides lots of benefits over IRC and would prefer it, though I could see IRC and Discord running side by side.
The other thing I think I have an issue with is people will use whatever platform they find the best for communicating and incorporating that communication channel into your own software can be a waste of time that can be focused somewhere else. I'd rather the devs just let the people use whatever they want to use to communicate and focus on improving the current software they already have rather than add features that won't entirely benefit the users or the software (it could make it more difficult to maintain and requires extra features and resources).
Your community is what drives your product, and what you decide to focus on will have big impacts.