I'm guess the absence of development teams is due to the fact that text games aren't typically made for profit. You'd really have to amass a group of people just doing it for the joy of it. Further, being involved in the programming side of it affords the writer of interactive fiction a deeper understanding of how their game works, and avoids them having to implement their vision through intermediaries.
That all said, I've helped produce
two prizewinning games through different partnerships, and I'm currently taking part in two collaborative projects, the
TMBG Tribute Album, and
IF Whisper 5: the benefits of working with others are clear to me, but then so are the downsides. When you work with other people you agree to forfeit full control of the creative vision for the project, and you leave yourself open to different levels of quality and commitment from your co-creators.
It's at least conceivable that a larger collaboration with people having more specialised roles could produce something interesting. I remain open to being convinced.