Wait, do you mean something positive by this? Discord has always struck me as pretty horrible...
I'm not even quite sure how to interpret what you've said in a positive way. Maybe implied popularity, but it's debatable whether popularity is in fact a positive even.
Sure, it's against the TOS, but I've been using an external client for probably 2 years and haven't been banned or warned. If Discord are aware then they've explicitly chosen to do nothing.