Why senior engineers get nothing done

I struggle with this. Part of the problem is that engineering (therefore the group of senior engineers) somehow always become the first-tier technical triage for problems. A customer reports a problem, a PM gathers more info, and then it's immediately thrown onto the queue of headaches that every single senior engineer is on the hook to fix. The ticket invariably gets round-robin assigned to a random senior engineer, who now has to drop everything and context switch over to debug mode.