Traction control was allowed before 2008. The problem was that it trivialized some aspects of driving - drivers could floor the throttle through turns at little to no risk. (I suspect there may have also been some concerns that drivers who pushed traction control too far could have easily ended up in unrecoverable situations.)

There's some interesting discussion of the history and technical aspects at: https://www.f1-forecast.com/pdf/F1-Files/Honda/F1-SP2_25e.pd...