The people who make a paper have to know where the border is for their particular paper. That is, which things in the paper are claims with evidence to back it

The people who make a paper have to know where the border is for their particular paper. That is, which things in the paper are claims with evidence to back it up - and which things are speculations about what might be an explanation. That some things are speculative is not such a big deal, as long as it is clearly marked as such. Then someone else can investigate it properly in another paper. Or people can use it in another work, by treating it as an assumption that they can verify whether holds, and then make use of.