Alumni from Graduate schools
Alumni, meaning students who attended their school as undergraduate students. I have heard the reason is because they want more of a variety of students from other universities or want to give others opportunity.
I firmly believe this is not true for many colleges. First by the nature of colleges and people there will be diversity. Some people will not apply to their college where they obtained their BS since they want to have degrees from two different colleges. To me it does not matter. When some one looks at your resume what matters most is your attainment of the degree, if it was accredited by a regional agency, and the rigor of the curriculum that you took at that college.
Graduate schools requirements
As a person who has attended 3 diff colleges – grad and post grad – my response to that would be no. A college looks to if you meet the requirements that were set forth for entry into that program. Also, if you pass the examination (if they have one) into that respective degree area. Some programs require you take an exam after you take about 3 to 4 classes.