We did a study for a major university after it found a huge increase in traffic volumes within its main entry “plaza”, and an associated logjam that radiated from there. A large proportion of that traffic was due to ride-sharing drivers circulating in and around the plaza waiting for passengers.
The university built a dedicated ride-sharing area nearby and prohibited ride-sharing services from the plaza. This largely solved the problems (although enforcement is an ongoing issue).
Ride-sharing absolutely can cause local increases in congestion if nothing is done to accommodate it. However, it’s a modern reality, so planners who don’t accommodate it aren’t doing their jobs.