Yes, it's used too often. Yes, it's used sometimes when it's inappropriate. Yes, sometimes I suspect that the author doesn't really know the answer. I'm less sure that the author uses it it all seriousness when the know the result is unproven or unprovable.

But it is a phrase that has its place, there are times when it's exactly right to use it. Don't reject it outright. I've used it in publication where the editor actually asked me to remove details and put the phrase in its place.

It's not always the author.