Not comparing Koeman to Michels for managerial achievements, but interesting that they both have/had an authoritarian streak in common with the flip side of enjoying a joke at times.
Have not heard Koeman speak of who his influences in management are, but surely Michels features prominently. What a great coach. Arguably the best ever.
The Dutch are just far more direct and don't suffer fools to the extent that is noticeable elsewhere. Having a European Championship winners medal with Holland coupled with the sheer extent of his playing/managing career in his homeland, Koeman probably feels more entitled than most to air his views.