I don't know your program, but I can imagine a practical program such as auto mechanics, where a competent person should be able to do everything. Would you want a mechanic who only knew 75% of the basics? And I don't think 75% in first year biology would impress medical school admission people, another example. People going to med school already have a degree but go back and take first year bio and chem, I know, and 75% would be an embarrassing grade, even though I was okay with getting just above that in human biology because I'm not a med student. (Ick.) So I guess it all depends on how the course is structured and the purpose and significance of the particular skill. I don't think that is generally a grade structure.

Another example. In my school if you get less than C-, you can't take the next course in the series. A lot of people scrape by with C- in calculus, but not math majors. Obviously for them that would mean rethinking their major.