This is not correct, to get flexibility all you need to do is buy the cheapest refundable fare, not a B or Y fare. At my previous job, all I ever bought was the cheapest refundable fare, which if bought in advance usually it wasn't that much more than a refundable fare for business travel (i.e., no Saturday night stay). During that time I almost never flew on B or Y fares, even though all my tickets were refundable. Usually they were M or H class, sometimes Q, and even the occasional refundable K fare on Southwest routes (those are all Delta fare classes BTW). It seems to be a fairly common misconception that only B or Y fares can be refundable, when that is fare from the truth if you buy in advance.

Any refundable fare still allows you to standby under the new rules implemented by the major carriers, in addition to allowing a full refund at any time of course.