I would say they have their use along sides other methods. If that's all you get, then no, it isn't good enough.
However alongside say comments (as someone put earlier "They're struggling at understanding fractions"), looking at past improvement, possibly (for teacher only) how they're improving relative to the rest of the class and other things they are useful.
I was talking to a friend not very long ago. She was telling me about her ds who is playing the clarinet. He's apparently absolutely brilliant and she's quite put out that the school hasn't acknowledged how special he is. Thing is I know a bit about grades. And I know that doing grade 1 after 3 years and taking 2 more years to do grade 2 is well below what you'd expect. She has no knowledge of music grades at all, and thinks that they are doing far better than 90% of children would. I'm not going to say anything, but I do think the music teacher should have given a little expectation managing and let them know it is not outstanding progress. At some point they're going to discover it, and it'll probably hit the child hard enough to stop them playing.
That's how I feel on school subjects. I have no idea what level my dc are working at. If they said "they're currently at this level in year 8, then that means nothing to me. Does it mean they'll be scraping a (old money) E at GCSE or pushing an A*? Should I be encouraging them to drop it when they ask, or saying it could be an A-level subject.
You could say that I don't need to know. But in which case, why do I need to know anything about their education, except they're there and not being a pain?
The point flight paths miss, to me, is where it is taken as the be all and end all. Where if a child is coasting and hitting their target it isn't picked up that they could fly over the target. Or if a child has for whatever reason started struggling, they're not put in the position of being thought not to be trying because if they were they'd get be doing better.
No way is going to be perfect to apply to imperfect schools and varying children. Any method of assessing that might suit one child may be a disaster for another.
What are OFSTED suggesting instead if they don't believe in this one, because unless they come up with a solution that is better for most children then surely this imperfect method is better than just not using anything?