It sounds like his skepticism is more of an explanation why some districts have been successful with this approach and others have not. The ones that haven't been successful seem to treat it as just a new program instead of a completely different operating system. For example, this district:
Denali Borough School District removed the system from two of its three schools when teachers complained that tracking student progress was becoming too burdensome.
They got rid of it because it's too hard to track student progress? Ugh

The time-based system is what we have now as opposed to the standards-based system.
In a standards-based system, time becomes the variable and learning is the constant," Selleck said. "When a kid can demonstrate proficiency of a standard, they move on. There is nothing magical about a quarter, semester or the end of school. That becomes blurred. Learning becomes much more 24-7.
Time based system: child can't take algebra because he's only 8 years old
Standards based system: child can take algebra if he's shown proficiency in pre-algebra
Sounds a little like homeschooling
If one of the toughest issues is not giving grades anymore, I'd be happy to go without my child's report card in exchange for her being able to work at a challenging level.
