Have you noticed that a new measure group is automatically created if you have created a new measure with Distinct Count usage? Microsoft Analysis Services create this not because of anything else, it is for improving the performance when it comes to specific analysis such as how many sales reps have sold a particular product.
You can create one with Cube Designer -> Cube Structure.
And once they are created, separate measure group are created;
And I will be able to see how many employees have sold a particular product in each year;