TL;DR: Leave the tag, things are fine as is.
The conversations tag is the most broadly use on IPS
As of now the tag makes up 536 of our total 2,968 questions, or roughly 18.1%. Looking at a well established site like ELU, their top tag makes up 15.5% of their total questions. WorldBuilding's top tag makes up 22.9% of their total questions!
So I'd say having a broadly used tag or a "niche" for our site definitely isn't a bad thing. In fact, I'd say 15-20% is probably right in the sweet spot of where we should be for a most used tag.
this tag doesn't bring any information at all.
Quite the opposite! This tag tells us that either the problem is occurring from a conversation, or the OP's ideal solution is some form of conversation.
Almost every interpersonal interaction could be described as being part of a "conversation".
The Wikipedia page defines "interpersonal communication" as anything that facilitates the exchange of information between two people. So I would disagree with this.
I would also define "conversation" as being a longer back and forth between at least two people. There are many questions here with answers like "Be stern and say no, don't allow for a back and forth." These in my opinion, are not conversations.
In summary, I don't think it's a bad thing at all that we have a big tag on the site. The tag does in fact bring important information about either what's happening or what the OP wants. And while conversations may be common in interpersonal interactions, they are by no means necessary--this isn't an all-encompassing tag.