In the short time that I've been a member of the community I've noticed that the OP sometimes doesn't tag their question with the RDBMS (go figure :)). Community members often ask for this information in the comments and/or the OP leaks the data via their question or comments. I have edited a question to add a tag 5 to 10 times in the short time I've been a member. At the same time there are community members with more rep/seniority who surely noticed the missing tag and had the information to apply the proper tag before I did.
I'm not trying to say that everyone should add RDBMS tags to questions. I understand several factors can be in play such as; time constraints, effort/reward/community benefit judgments, a feeling that it is not their place, low perceived value based on the substance of the question, I don't have the rep to see they already did edit to add the tag, etc.
My question is there a purposeful reason why they are not editing the question to add the tag? Or worded differently; is there a reason why adding a tag is detrimental? I only see benefits from the tag which makes me wonder if I'm missing something, because most things are a give and take.