The latest issue of Bloomberg Businessweek offers another poke at those who promised that the Affordable Care Act would not stop people from keeping doctors and health insurance plans that they already liked.

Ben Rosenthal was treated for prostate cancer four years ago and had gallbladder surgery the year before that. A former manager at a market-research firm in Los Angeles, Rosenthal, 57, paid for his own health insurance. Last fall, when his plan was discontinued because it didn’t meet standards set by the Affordable Care Act, Rosenthal bought the best insurance coverage he could find, a top-tier “platinum” policy from Blue Shield of California that costs $792 a month. He figured it would provide access to top hospitals. Then in February he learned the plan wouldn’t cover the hospitals where he was used to being treated.

Rosenthal is one of millions of Americans who have purchased insurance under the Affordable Care Act and are discovering that many of the new plans offer a narrow network of doctors and facilities. “If I had anything happen, I wouldn’t want to go to a hospital that I’m not familiar with and with doctors I don’t know,” he says.

Since the ACA created marketplaces for private health plans last fall, insurers expecting to lure customers with low premiums have fashioned smaller networks of medical providers. By cutting out expensive hospitals and negotiating favorable rates with doctors in exchange for sending more patients their way, insurers can keep premiums down. Blue Shield’s new network includes 43 hospitals in Los Angeles County, about 64 percent of what its standard coverage offers, spokeswoman Lindy Wagner says in an e-mail.