The reason is convention. Just as in English you could spell 'I' as 'i' and it would probably make no difference but the rules tell you to use 'I' because it is the conventional, the 'right' way.
In Russian, the convention is to set off subordinate clauses with commas. Потому is part of the main clause and что belongs to the subordinate clause, hence the comma in between. Notice that there is also a comma on the other side of the subordinate causeclause - before и in your example.
As a rule of thumb, putting a comma in front of что will be correct in 90% of cases. Many people do it automatically. There are cases though when no comma is needed. E.g. when two subordinate clauses are joined by и with no part of the main clause in between:
- Не потому, что я из России и что я организовываю.
Notice no comma before the second что.