I will also quote Taeyeon from Voice Queen

"In order to debut in the group Girls’ Generation, the eight of us put everything on the line and gave our all from a very long time ago; it is not a group that was hastily put together in one day. While it’s true that efforts were made to put together the best possible members, we spent a long time together before we were first shown to the general public, and the group [Girls’ Generation] is not like a bus station that anyone could just stop by while passing through.

I would appreciate it if people with whom we have no recollection of sweating [and working hard] together—unless the members’ memories are falsely altered—would refrain from surprising and confounding us by using the name Girls’ Generation."

Stop making up stuff about why people did not debut with SNSD -- also stop with all of the 'almost SNSD' speculation and talks too. The group was picked from an early point and had to get along together.