I didn't say there was a need for the dev to give an explanation, nor did I imply that they should feel obligated to do so. I said it would be nice if they did.
OK, you're still not grasping the premise.
No need = there is nothing to be gained by the dev putting the definition there.
The definition will need to match what the rule's definition is, otherwise the tag cannot legitimately be applied on this site.
So, if you're confused by what a tag might mean, or the circumstances under which it can be applied, just read the rules.
The site's definitions are all that you need.
The incest tag is not ambiguous, in any way. The conditions under which it can be applied are clearly stated.
Any family member, not necessarily blood-related. Step\foster\adopted\spouses of blood uncles & aunts.
All qualify for the incest tag.
If you want to know whether it's strictly blood-related in the game, then just use thread search, or ask.
Again, what you're saying "it would be nice to have" just amounts to extra work for the dev in order to cater for user ignorance, or laziness.
I consider that unreasonable, but I think we'll have to agree to disagree.