opting out of ACA exchange isnt about whether or not they must accept insurance. some states decided they do not what to expand their medicaid and medicare programs (lower their income bracket requirements) and they have their own websites where people in their states can sign up for various health care options rather than sending people to the federal website to do that.

short version many dont want the hassle of only being able to use website option a few days out of the year (healthcare.gov is only open so many days a year for people in the USA to register and "shop" for insurance where as individual state websites are "open for business" every day 24\7)

yes there still are a rare few that are still on the no insurance way because it takes time to get certified and get insurance companies to agree to add that physical or mental health agency to their list. insurance companies have a budget to follow and if they have reached their budget then they have to tell an agency sorry we cant add your company to our plans we can put you on the waiting list for a future agency listed with our insurance company.

line in the sand when obama care went into affect it didnt only affect clients, it affected treatment providers and insurance companies alike.

those you see that dont accept insurance probably have not gotten their certification for doing that or are waiting for insurance companies to agree to have them on their list of who they will pay out to.