Possibly. There was a study on this in Oregon, and the data suggested that people who use the ER for their primary medical care keep doing so even after they're insured: https://www.npr.org/sections/health-shots/2016/10/19/4985261...
People who self selected for free medical care didn't have much better health outcome than others who were not selected, except that they didn't go bankrupt.
So, the group that didn't get paid for didn't go to the ER, while the group that did get paid for went to the ER but didn't have better health outcomes than those that didn't. Surely that says something about the private, for profit institutions that run the ER business.