Turbo,
Using your logic: the side of the rocker closest to the spacers separating the rockers would bind because that area is between the shaft hold downs & is unsupported.
There's a difference between a seated stationary shaft and one loose enough to move. That rocker shaft was loose, and was loose for more than a few seconds or minutes as those rockers destroyed themselves.
You've got a shaft that would be moving around, with counteracting forces all along it. We're not talking about those forces located on a stationary section 3" long with only two rockers on it, but potentiality the whole length of shaft with all eight.
How much does it take in that situation to make the shaft deflect and close up the .001 clearance?
Again, all of that, and no chance but you think a 3/8 bolt and a stamped hold down can?