Of course, marketing affects visibility. Selling to a broad customer base nationwide requires high profile advertising. Much of the success of major manufacturers could be attributed to their advertising genius combined with excellent products. Kerr's marketing strategy focused on banks and other institutional customers, although the company also sold some pens nationwide through stationery and office supply stores. Parlette, as far as we can tell, had a very small regional market and didn't sell many pens to begin with.
Collectors are also less interested in less common pen brands.
Because of Kerr's institutional niche, few pens ended up in desk drawers to be forgotten until a move or estate sale uncovered them. Institutional pens did not become family heirlooms since their purpose was not to mark graduations, holidays, engagements or marriages. No doubt, most well-worn Kerr pens were unceremoniously tossed into the trash after their users received full service from them. For all these reasons, few Oklahoma-produced pens are in vintage collections today.