If you started with a chain complex in an abelian category, then the spectral sequence you get out has to degenerate at E_1, and I'm guessing that means that the objects F(i, j) are zero whenever j - i > 2
A chain complex in a stable category gives you, in particular, a filtered object, and as Lurie discusses, the objects F(i, j) for general i and j are related to the higher pages of the resulting spectral sequence
You can write down a sequence of objects in a stable oo-category with boundary maps such that d^2 = 0, but then there are a bunch of coherences you have to put in, because d^3 otherwise might be zero in two different ways
I don't know how plausible that seems to me, but some rich and powerful people seem to want to make it happen, because there was a link to the breakthrough prizes from the main google search page the other day
@JonathanBeardsley there is a potential utilitarian calculus here. It could be argued that if the breakthrough prizes really "arrive" in the public consciousness, they could raise the profile of math enough to draw vastly more funding than their cost
ok, let's see - is it the case that left completeness is equivalent to the mapping space between the Postnikov systems being equivalent to the mapping space of spectra?