What's the reasoning here?

[Korpsy Knievel]

I d believe that pasteurization kills probiotics that could be useful

Nutritional changes wrought by cooking are much more sensible and likely-seeming to me, too, since that tends to be the general case.

but I'm more about the grass-fed local thing than anything else.

While living in the boonies where said dog herded said goats, I bought milk and ice cream from a local dairy when possible, though they did pasteurize. It is quite nice to know the people and the methods that produce one's food.