^^ yes of course but then again, try to get your “average” (not “CC average” but C average) child into the MYP at a private or magnet school in the US.
It’s true all children could benefit from participation and in other countries the IB diploma program has various interations, including a vocational version, but in the US the IB program tends to be much more demanding than the average middle school program and is managed accordingly.
For the record, I find the way the MYP builds subjects through years 1-3 then 4-5 excellent. It could be a good example to follow as a general curriculum, especially for Math and Individuals&Societies, but it’d have to be slower paced and less demanding for most students.