It seems reasonable to not waste time on 1 in 1,000 customers who experiences some issues, especially, when it is not clear what the issues are. However, in reality, it has more of ignorance rather than rationalism.
Even 1 customer asking for a help is worthy to get away from the routine and think what can be done in his unusual situation. For example, when it comes to SaaS issues, the simplest solution is to replicate the steps on the customer's side and see what the logs of console or product show, and if this does not help, then ask for support from the technical department.
On the one hand, you spend some resources, while, on the other hand, you do not leave the user alone with a non-working platform. By doing so, you will save the customers and build a reputation of fearless and sincere support.