We do try our best. I think you may have pointed out the flaw in our system though. All support incdents are free and unlimited. We had tried having them expire after a year and giving a certain number in the past, but customers complained, so we changed our system.
As a result we get a lot more incidents, and a lot of them do involve teaching our customers general concepts about PHP, mySQL, HTML, CSS, Dreamweaver, or the web in general. We do take on a heavy burden when we try to not only make sure that our products work, but we actually try to make sure our customers are successful with them. Very few companies go as far as we do to ensure our customer's success.
However there is a valid point that we end up spending a lot of time in support helping people do things that they can't do not because our products don't work, but because they don't know how to use them. As a result someone that has an obvious question or bug reported may not get an immediate response as we are working to help other customers.
There is another delicate balance we keep between answering all of the questions thoroughly and answering all of the questions quickly. We certainly spend a lot of time thinking about support, a lot of energy providing it, and have a lot of resources working on it, but support is a pretty thankless job I did it for over 10 years so I know.