Martin Fritz Huber of Outside looks at the issue here.'
https://www.outsideonline.com/health/running/elite-starts-major-marathons/
For me, there is no good reason to have the pro men start separate from the masses. I think it's kind of a hidden way for them to control the number of Amercans finishing in the top 10.
Some might call it racist. Personally, I don't think they are racist at all and think that term is used way too often in the US. A race is thrilled to have a Meb or Elkaneh Kibet do well as they are American, but they don't want an uknown African finishing 6-7-8.
I get why they do it but don't like it.