@chez311
of course agreed, but it is done all the time in manufacturing, theoretically datum -c- could be probed by CMM
but it is easier by location on and opposite face the 3 datums verified, 3 constraints established. dimension will be held
by manufacturing to a tighter tolerance for tooling so that the engineering drawing requirements fall in.
at the end as specified on the drawing the requirements are satisfied. I have and still do this often.
there is tolerance stack up, and is common to tighten the dimensions on the print to allow stack of dimensions to fall in
and it can and does get complicated.