It means you are sentencing future generations to pay for your social programs if you never pay it off.
But aren't future generations benefitting from us building a better world? That is the point of social programs isn't it?
It means they run the risk of being buried by debt servicing costs when interest rates rise.
What about the risk of destroying the economy by things that cause interest rates to get out of control?
Don't let them rise the by doing as MMT calls for; ensuring politicians and their parties retire debt during good times as they're supposed to instead of spending on their pet projects. If we can't get better control over our governments then of course things will blow up in our kid's faces...just like they blow up in our's.
The key to everything is more rigorous robust institutions of accountability. Think of these as being like control rods in a nuclear reactor.