Why is the standard Bayes factor test for directional hypotheses against the point-null?
In the JASP software as well as in the BayesFactor R package with the ttestBF method, the standard Bayes factor test is testing an alternative against the point-null hypothesis.
Assume we want to test the directional hypothesis that d<0. It seems to me that a frequentist analogue (i.e. a one-sided paired samples t-test), would test the hypothesis d<0 against the the null hypothesis d>=0. However, the standard Bayes factor test would test the hypothesis d<0 against the the null hypothesis d=0. Why is this the case? In what cases would be interested in such point-null comparisons?
I am aware that the Bayes Factor test that d<0 versus d>0 can be obtained by dividing the Bayes factor of the defined null interval (-Inf<d<0) and the Bayes factor of the complement of the interval !(-Inf<d<0), so I would be glad to hear your thoughts on a conceptual level.
Thanks in advance!