No problemo. They can offer you electricity closer to the marginal cost of producing it .. AT their plant. You are free to take it somehow and deliver it where you want, the way you want, at costs you want. If it hadn't occured to you yet, then crucial function of regulation is to force development and maintenance of distribution network, that means wires to your home, your town, your area, country, and protecting you from paying insane money to get your electricity to your home.
When costs begin to relate to differentiated pricing. Already the case. To get the nines, you pay extra. What you have by default, is a free lunch, payed for by someone who needs the nines. No room for whining, be it down for a week if they like. Epic blackouts impact whole economy, thats why they get the front page.
Have you ever owned UPS? They need all the nines because downtime costs them money, much more than all the nines they pay for. Please name one crucial business that can run without energy in todays world.
How many CFOs today seriously consider building nuclear plant to SELL electricity instead of buying it? Who cares what it costs if its compensated? The only "CFOs" who will seriously consider re-engineering their processes are residential losers who will take advantage of the cost-saving choices to find more opportunities in whining about the choices. Perhaps also that it has damn rare major blackouts.
And, seems its not obvious to you that "nines" are not function of production of energy, but of reliable distribution of it. By competitive supply market, you are implying alternate distribution network, grid. You are welcome to build your own nationwide grid thats better, cheaper, more flexible. There are thousands of energy suppliers waiting for you.
Nothing has happened there. Planes are crashing, banks are robbed, telecoms have outages. Unique to energy sector is that every damn business stops without energy.