Can someone tell me what the actual point of US Nationals was?
Off the top of my head, not in any particular order after the first:
To determine national champions in each discipline, at senior and junior levels
To be the most significant (but not only) data point in the selection of Olympic, Four Continents, and Worlds teams
To be a significant data point in the selection of this year's Junior World team, for selection to funding envelopes and the International Selection Pool, and for actually selecting skaters for other international competitions for the rest of 2022
To fulfill contractual obligations for network broadcasts that fund much of the organization's activities (how much money would be lost by canceling on short notice?)
To fulfill contractual obligations to ticket holders (or be forced to refund that income)
To gather many (in some disciplines most or all) of this year's top competitors at junior and senior level in one competition in the same time and place for a meaningful head-to-head comparison among those who compete -- which in some disciplines does not happen at any other time of year
To allow skaters who qualified to Nationals (perhaps for the first/only time) the opportunity to actually compete at the big show.
To gather past stars together in one location and otherwise to celebrate the federation's current and past successes
To provide opportunities for current national officials to get meaningful officiating opportunities, and for not-yet-national officials to train toward national appointments
To gather officials and top competitors from the qualifying season at lower levels in one location for the national high-performance development camp, along with an opportunity for the potential stars of the future to watch the current stars
Why hold a superspreader event if it didn't even matter?
It matters for all of the above reasons, even if it didn't matter as much as some might prefer in terms of one of those purposes (choosing the Olympic team).
Some of those purposes could be given up if necessary due to health and safety concerns. For example, no spectators last year. But not holding the event at all would be a big loss to many stakeholders, including fans but more important including dozens of skaters.