The article I read was that residents of Texas can select among over one hundred suppliers. That's pretty free. Years ago, everyone was stuck with one supplier and one price, take it or leave it. Then many states opened it up to the free market and allowed competition. Competition brought prices down. I save about 2-3 cents per KWH over the utility company that ordinarily serves my home.
I looked at some of the NJ fixed rate plans. Some lock you in for 6 months, some 12 months, and some 24 months. Within those three time periods, different suppliers have different fixed rates. The rates didn't seem all that far apart. I guess if you have a spreadsheet, you follow energy futures, and you are highly motivated, you can save some money. The next time I get my electric bill, I'll check my kWh usage and multiply that by 2-3 cents and see what I could save if I had a choice too.