The Big10 commissioner wanted to see if they could “sway an election” by not playing. The pac12 has no leadership and just took the easy path by following suit, as did the MWC. This blew up in the Big10 commissioner’s face, so the Big10 panicked and rushed back.
The pac12 realized they couldn’t be the only one not playing, but half of their teams had been sitting on the couch for months at that point, which scared them away from an October start.
The MWC wanted to be bold and start when the big 10 starts, but they don’t have the resources, pressure or backing to make it a smooth transition.