At MSRP's of $7.00 for freight cars, $8.00 for the EV caboose and $30.00 for the F9's this first O Scale attempt for Atlas was a bargain in the early 70's.
Although it was all pretty lightweight stuff. I suspect it failed because it didn't have the "heft" O Scalers were accustomed to.
A good article about Atlas/Roco O can be found HERE.
Rusty