Let's say gcc gave me and odd error on an Ubuntu version which is off topic like 14.04, 16.04 and all but gcc runs in on topic versions too. The problem is a general Ubuntu problem even if it occurred on a non supported machine. Is it okay to ask a question about it with details or examples like given from my system?
It may be said that it is fine if it can be reproduced in supported versions but sometimes it can't be known. You can't predict if your problem with be reproducible.