I base my opinion here on my experience with the Python discord, which is probably one of my favorite haunts these days. It excels at helping newbies, of which there are many each day, because their questions are quick to answer and can be handled almost instantly by any decently experienced active user. It's the more specific or advanced questions that languish there, because it's less likely that someone experienced with that particular domain will happen to be online. It doesn't need to concern itself with archival quality because no one expects answers to be referenced later.

So I think both types of communities can play to their strengths without diminishing their quality. The chat rooms can answer the simple, open ended questions that don't bring value to SO's database of knowledge, and the more complex and advanced questions can have a better chance of being seen and answered with valuable insight on SO.