From 1957 to 1965, John Romita worked for DC Comics. Although he dreamed of working on any of their more recognizable adventure titles, he found himself stuck in DC's romance comic department. Years later, of course, he would become the architect of the "Marvel style" and go on to have some 35 successful years, working on characters like Daredevil and Spider-Man.
Editors at DC were very territorial. They had their own stable of creators whom they never shared with other editors. A freelancer could lose their job if their editor found out they were working with someone else.
Freelancers who needed more money, or who wanted to work on different types of books, took to using fake names to avoid the backlash. A lot of these, like Romita, were artists languishing in DC's romance department. They all began to quietly seek work from Stan Lee.
Says writer and former Marvel Comics EIC, Roy Thomas:
"Gil Kane was "Scott Edward," and Werner Roth was "Jay Gavin," both named for their kids. "Mickey Demeo" was Mike Esposito, and Frank Giacoia was "Frankie Ray." Stan [Lee] and I would chuckle about how DC had had all these great hero artists buried in their romance department. It wasn't that DC was disorganized. It's more like they were too organized to utilize their artists well."