Let me rephrase, the modelling for ridership always showed downtown Brampton being much more heavily an origin station in the morning, and a destination in the afternoon. There is an abundance of parking in downtown Brampton, the City owns in excess of 2000 spots. At peak demand before the pandemic, there were still 700 parking spaces free.
Why would people want to go to downtown Brampton, what is the draw? The nearest residential area along Hurontario in Mississauga is at Matheson. The distance between Matheson and Brampton GO is further than the distance between Matheson and Port Credit GO, so if I want to go to Toronto, Port Credit is easier to get to. If I want to get to Guelph, I could get a GO bus from Square One. If I want to go to London, then catching the 3x a day to London train via Oakville would probably be more convenient than catching the one per day train to London via Brampton GO. There is a very large employment area in Mississauga between Brampton and the northernmost Mississauga residential area along Hurontario, this means there is far more to draw Bramptonians to Mississauga, than there is to draw people from Mississauga to Brampton. That will enable significant growth in office employment in Mississauga, stifling employment growth in Brampton. With the current costs of the LRT, this would mean there is very little gained by Brampton, yet much gained by Mississauga.