Wicht
Hero
I believe it went:
1) WotC pulled the magazine licenses and Paizo had to scramble to reinvent themselves.
2) Paizo started their Pathfinder module APs
3) WotC anounces 4e is coming.
4) Paizo doesn't want to have their business shackled to a revocable license again.
5) no license or pre release 4e rules for 3rd parties like Paizo.
6) Paizo finds making 3e OGL stuff working for them.
7) Paizo concerned about core rules for their modules going out of print.
8) Paizo decides to make their own 3e compatible Pathfinder OGL core rules to have it in print.
9) Paizo starts open playtesting Pathfinder.
10) 2008 4e comes with no GSL, only 3rd parties not using GSL come out with limited 4e stuff (Goodman, Adamant, Kenzer)
11) March 2009(?) revocable and changeable at will GSL comes with OGL poison pill provisions for product lines
12) Gencon 2009 Pathfinder released.
13) Later in 2009 GSL revised to remove poison pill provisions.
I think it was an early decision based on a combination of not wanting to be under a revocable license after getting the magazines yanked combined with expertise and ongoing success with making and selling 3e stuff as well as the inability to count on doing 4e stuff.
# 10 should be moved to just after #7.
and #4 should probably be moved to somewhere around #7 or #8 as well.
The failure of the GSL to be released in a timely fashion occurred before the announcement of the open playtest. Also missing is Paizo asking their fans which way the fans wanted them to go. Paizo was openly trying to decide whether to support the new rules or not. It was never a foregone conclusion with them and they have been pretty forthright in saying that at first they were weighing all their options.