from Fancyclopedia 2 ca. 1959 and Fancyclopedia 1 ca. 1944
One of the cutenesses of modern decadence is unuse of capital letters. This is strengthened by the fact that distinction between caps and lower-case is unnecessary. Sometimes it stems from a pun on distaste for capitalism by Bohemians, but considerable vers libre, as well as beardmutterings and other art forms, habitually appears in solid lower-case. A practice of damon knight's is to spell his own name without caps, and in the mock wars — First Staple War and FooFooism vs Ghughuism — omission of capitals in referring to the enemy was practiced by some of the combatants.

from Fancyclopedia 2 Supplement ca. 1960:
Another use for this custom is as an implied apology for using stock phrases or, conversely, to pretend that a phrase is stock; e.g., Real Artistic Writer. Speer dislikes this custom, because he always feels impelled to stop and see if the initials spell something.