There are many people out of the academy who can still be understood as contributors to the field. There are various cases of non-doctorate holders who have come to make contributions to mathematics. Thomas Bayes was a pastor who had come to create a very important construction of probabilities used and talked about from areas disparately far from mathematics like computer science and philosophy. Marjorie Rice was a housewife who came up with a notation for looking at tesselations, and perhaps the most notable amateur mathematician was Pierre de Fermat.
It is a sign of the times of increased instrumental rationality and Mcdonaldisation (look it up) that our developments are limited to the academy. But this is changing somewhat. Philosophy, for instance, is branching out to the bloggosphere. One of the most interesting developments, a movement called Experimental Philosophy (X-phi), debaes their most contraversial tenets on public blogs. A few journals are opening up to public consumption, and a small number of scholars choose only to publish on journals with wide access.
Incentives like the Gutenberg project, wikibooks, and Jonathan Bennett’s historical translations, open up scholarship and very serious learning to those who seek it out. Let us not forget that Frege, during his own tenure, was too poor to purchase Russell’s Principia Mathematica, such that the latter had to hand-write whole passages of the work.
We should remember two things. One, our current organisation of learning has only being such for a short period of time in the history of the intellect. Two, our conception of learning and structures beneath it, are not the only way to be.