The cynic in me says
(i) having "everyone, even the CEO" help out with customer support is a good motivational device to emphasise in what might in every other respect be a substandard customer support working environment
(ii) paying regular customer support staff at the low end of market rates is one way of recovering the imputed financial loss of having your $100/hour senior engineers and top bizdev staff focusing a part of their working year on basic customer support queries...