No...your right there DRT.....in fact some straw seems to carry quite a few weed seeds in it.!!
It's just that straw is one of the cleanest materials for protecting the fruit itself and it doesn't 'pond up' if you get heavy rain falls where some heavier mulches might.
Also , being such a light material, it's far easier to apply than a lot of others.
An apple a day.....keeps me in work.