Every human uses different messaging services. For me Discord is very crucial for school clubs. It's integration into Opera GX is a very useful featur, and see why not it should be with Opera too. It would give a lot of ease of convenience to people like me.
Opera GX already has a lot of feature which Opera doesn't, and that's ok, to keep Opera lightweight, but feel like Integration of Discord to sidebar shouldn't be one of the excluded features for Opera.