I agree with Tom. In the '60s I had a Pontiac Tempest. The right rear brake shoes never wore at all but the driver's side did. I unbolted the OEM wheel cylinder and found, the hydraulics hole was never drilled. The rest of the power brake system worked just fine.
I would suspect, if you had a leaky vacuum booster sucking on the M/C, it could draw brake fluid into the booster and into the intake manifold. But, a blocked wheel cylinder acts the same as when the shoes are hard against the drum.
Can you tell us where on the net you found this info? - Dave