I think there is no need to use bitcoin on salary, it is more convenient if we used fiat because it will not going to rise or maybe fall so we can assure that the salary will be consistent. While if we use bitcoin we dont really know when the value drop or maybe rise so the salary will be no assurance to be consistent. so i beleive that using fiat has more advantage than using bitcoin in giving salary. However everyone can simply buy bitcoin after recieving a fiat salary It is all up to them.
It all depends on who wants to send or receive a salary,
Usually cryptocurrency activists prefer to be paid using cryptocurrency or bitcoin rather than fiat, because it is easier, faster and there are also transaction records which of course can be evidence when one day there is a problem.
and I personally, of the many transactions that I do or the salary I receive, on average use cryptocurrency (especially bitcoin),