Agreed! I’m part of multiple communities in-game which are rather massive and very active.
Some communities I’m part of either on Discord or even on social media sites such as Facebook utilize the in-game communities feature for members to signup for in-game events I find. My in-game calendar is always flooded with events to do as a result! 
Some players may prefer to use Discord for their communities because of all of the features it contains while others may use the in-game community feature. Player preference it comes down to. I personally prefer to use both platforms!