I will if I must but, hear me out...
Why put fat against fat - surely fat - sugar - fat, to make the best of all the ingredients.
Its a simple matter of science and engineering - butter first, this protects the scone against the osmotic effect of the sugar syrup in the jam, which would otherwise draw precious moisture from the scone giving it an unpleasant texture to the cut surface.
Then the jam, then a big blob of cream, because of course it's really impossible to spread the heavy cream onto the jam, you have to spoon/pile/blob.
This gives you distinct layers so you get all the flavour - gets the best out of the varying viscosities and spreadability of the three ingredients - allows you to pile on whatever quantity you wish (or dare) of each.
I am no fluffy headed jam first purist - if (for the sake of argument and it would be a terrible tragedy of course) one had NO BUTTER... and yet scones and jam and cream were to be had and it was an emergency...
Then cream followed by jam would be acceptable, it follows the 'fat before sugar' rule, waterproofing the scone surface against the sugar syrup.