I don't at my current job, but my last job did. The benefit of having them is that they maintain domain knowledge about how something works, will ask pertinent

I don't at my current job, but my last job did. The benefit of having them is that they maintain domain knowledge about how something works, will ask pertinent questions about new functionality, and are able to dedicate a lot of time to trying to break a component. The drawback of having them is that if they are mismanaged or get backed up, it can take a long time before a feature even gets looked at (my last job was so bad with this that I would often get asked about features that I submitted 4-6 weeks later). The good thing about not having a QA team is that QA becomes a much more active part of the process where something must be tested by the developers before it's completed. You also don't have a single bottleneck if the QA team is overwhelmed. The drawbacks are that developers aren't always very thorough and that their testing time takes away from their development time.