MA's roundabout route to single-payer?

So, the more I think about the MA plan, the funnier I find it. First, the rely on the private insurance companies, but require individuals to buy insurance and subsidize their premiums on a progressive basis. The insurance companies come in way above cost estimates because of administrative costs inherent to a private system. Now the "Health Connector" has rejected the $380 plans and demanded cheaper ones, while (at least for now) still enforcing minimum standards. Some are talking about price ceilings for basic plans and at least one person (me) is talking about capping administrative costs. The result of these suggestions, if enacted, is that many insurance companies will leave MA, but a few will remain and offer similar plans that provide the minimum required at the maximum price allowed. The individuals mandated to buy insurance will have the choice among a few very similar plans, at similar prices, but with extra administrative costs (because even 2-3 firms in a market will spend money trying to avoid sick people and market to healthy ones).

So we have:

• Mandatory purchasing
• Similar coverage
• Premiums charged on a progressive scale
• Little competition

Other than the higher administrative costs, how is this different from establishing a single-payer, "Medicare for all" style program? It seems like a roundabout way to achieve much the same thing, with all of the same so-called "drawbacks" (its mandatory and offers few choices), but fewer advantages.