Well, yes, until the stuff which has to be delivered by the people sucked in to do support stuff starts lagging and missing deadlines. Then, suddenly, lots of people start being really unhappy (usually at the expenses of the people who were helping).
If the oncalls don't have the knowledge to solve the issues they encounter, they need to escalate them and somebody needs to put more time in developing a more comprehensive knowledge base for them to reference, not just "steal" time from other company functions.
If the oncalls don't have the knowledge to solve the issues they encounter, they need to escalate them and somebody needs to put more time in developing a more comprehensive knowledge base for them to reference, not just "steal" time from other company functions.