I don't think the Speer company itself "discarded the handloading market." Instead I suspect ATK, which owns Speer, told them they'd primarily be making bullets for Federal and CCI ammunition, rather than for handloaders. That's what sometimes happens when a company becomes part of a much larger conglomerate.

“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.”
John Steinbeck