Not true. You need a comma before and when joining in one sentence two independent clauses, or complete thoughts. Example:
Joe will develop the presentation with Regina, and Mary will deliver it to
the committee members.
Without that comma in place, we would read the sentence as Joe will develop the presentation with Regina and Mary, then get stuck trying to understand will deliver, and have to reread the sentence for clarity.
True, a short compound sentence without a comma before and would be clear, such as, “I like you and you like me.” While the comma in these cases is optional, you can use it for consistency.