There is a curious case that resulted in bunch of questions that are tagged with one system, while the OP was confused about workings of a different system - and some of these tags were applied by OP himself.
Note: That I am posting this as an outside observer, and even though the other people involved are active members of the community I have not contacted them. So I encourage them to participate and feel free to correct me if I am wrong.
So our tale starts with this question: How can I get the DM to stop sending giants to kill us?. It was a well-received question by a first-time asker that was tagged simply dungeons-and-dragons. The community members helpfully changed the tags to more descriptive dnd-5e and problem-gm, which were initially rolled back but afterwards accepted. (Note:
I haven't seen where OP states that it was indeed 5e. The OP stated the system was 5e in a now deleted comment.) OP took note of it and changed the tag to 5e in the other open question at the time and in future only used dnd-5e.
And all was well.
That is until he asked this question: How can my level 3 party defeat a group of Liches? For anyone with any experience with 5e it was obvious, that something was very wrong with the situation. It looks like most of the community assumed that it was a problem GM or the system was heavily homebrewed, and it seems most took the dnd-5e tag (added by OP) as a fact. I (and I'm sure there were others) thought that OP was actually playing something other than D&D 5e, and out of curiosity, I mentally noted to check up later what system was he actually using.
A while later he asked this question: How do I gain magic as a Ranger? - and, in comments/chat, all but confirmed that the Player's Handbook that book he was using was not actually the D&D 5e Player's Handbook (although he never stated what was the actual system that he was playing, and I am still intrigued).
So now there are questions that asked about situation in system A, but were tagged with the system B - some of which were well-received, no doubt because situations seemed intriguingly crazy, while others were poorly received because they made no sense.
I also find it hard to see that there would be anyone to blame for this confusion. The initial edits were most likely done in good faith to improve the tags on the question. The OP probably didn't know he was playing something other than D&D 5e, and took the tagging suggestions to heart. If anything, most of the blame lies on the shoulders of OP's GM, who didn't convey what exactly was it that they were playing.
Additionally, as long there exists things like this PDF* (whatever that is), it is completely reasonable that we will get people asking questions who not only do not know which Dungeons & Dragons edition they are playing but can also cite the exact text found in D&D 5e books while actually using another system.
My question is therefore twofold:
- Does anything need to be done to the existing questions? Technically the tagged system is not the one the questions were asked about, but it is a mess.
- Do we need some kind of community guidance to prevent such a confusion from occurring again?
* I found it by using a Google search limited to PDF files on the overrun text mentioned in this comment. As it is a PHB, not DMG, I didn't manage to prove the original commenter completely wrong :)