I need to get a visa to travel to France for a seminar, however, the appointment date to submit visa application is after the date the seminar begins. Can I apply for a Schengen visa at the Netherlands Embassy, because I can get an earlier visa appointment date? And use that visa to travel to France for the business seminar?
That will not go well.
The Dutch consulate must refuse to even process your application once you tell them that your main purpose for going is the seminar in France.
And if you try to tell them that your main purpose is something in the Netherlands, then you have now lied in a visa application (and will need to lie again at the border when you are asked what your plans are), which has pretty bad consequences.