Even though technical implementation questions are off topic, we still have a few questions that deal with technical aspects. (List of all closed questions that aren't duplicates)
Mods can add a custom close reason for off topic and I think it'd be a good idea to do so. I understand that we still only have a handful of questions that are closed because of this, but it seems like a decent amount of closed questions in the future will be because of technical questions. We can make at most three custom off topic reasons, but we can also remove them if needed (doubtful this will happen).
Another idea would be to migrate these types to Webapps SE, since they have some questions about forums.