Is it a coincidence that a lot of the English 48-bar jigs are in D?

Here's a totally off-the-top-of-my-head-theory - as so many 48 bar tunes
either change key up/down a fifth, or go into the relative minor, in the B part, many 48 bar tunes start in D so that the B part is in one of Em, Bm, or G, and therefore in an 'easy' key(*) so that most instruments can keep playing all the way through?

* (yes I know D or G isn't an easy key on the Ab Pedantophone)