You'd need to ask the clubs involved. I don't see any advantage to it at all, but plenty of negatives.
Seems a bit strange as the season start is so long away players want a start date to aim for and ramp up there fitness etc to be peak for that time aimless training with no real goal etc can just breed the wrong mentality of just going through the motions however some of the players at this level might not have done any fitness work etc for months so could be doing with it
ps that is all hypothetical because they shouldn’t be training the now