QA is one of the targets of a CD deployment, in some case they can be the primary target. Every time you check in you have a new QA deployment made, that can then get promoted to UAT production etc.

Having a CD pipeline doesn't necessarily mean you are deploying to production multiple times a day. It means you can if you wanted to. If I have customers experiencing a problem that I can fix with a 5 minute, low risk patch then going through QA is nothing but a waste of everyone's time.

Also, a lot of the traditional QA work would be automated.