Remember that PACER is not intended as a site to research cases, which tends to be how many lawyers use it. It's meant as a site to organize electronically submitted court documents for the judges and the lawyers for a single case, instead of a paper file. The people involved in a case are going to be looking at all the documents for one case, and that is all nicely organized on one docket page. "Following a case from court to court" is not the intent of the system.