I never recalled anyone telling me that I had to have a dedicated confessor
It’s advice that I’ve seen given to people who are trying to progress in their spiritual life, for example, those discerning a vocation, those in a religious order, etc. The idea is that the confessor gets to know the person’s habits and sins and so forth over time and can provide better advice.
As a practical matter, it does not make sense for every Catholic to have a dedicated “regular” confessor. Let’s say there is 1 priest assigned to a parish with 500 parishioners. Ideally, all of those parishioners would go to confession regularly, let’s say they go every month or two. That means one priest would be taking on the burden of 500 confessions every 2 months. Even if he was able to hear 10 confessions an hour (6 minutes per confession), he would still be having to spend the equivalent of a 50-hour work week every other month, just sitting in the confessional hearing confessions. The only way confession is continuing to work with the limited number of priests available is that many if not most parishioners do not go very often.
On top of that, even those people who have a reasonably “regular” confessor, perhaps because he is the only priest assigned to the church, are likely to have to use a different confessor sometimes when their original choice gets reassigned, retires, or the person is temporarily or permanently in some other part of the country.
Many confessions are going to continue to take place at the venues where confession is made a featured part of a day out at a shrine, or a retreat, or a holiday penance service, and they bring in anywhere from 5 to 20 priests from all over the place who you’ve never seen before and never will again, but they get the job done of hearing the individual confessions of a large number of people.