Could it be all the old games have their legs bolted directly to the cabs, so the more you tighten the leg bolts the more it presses the corner together against the legs, Stern cabinet splitting seem to have started since they have been using those decal protectors with the legs spaced away from the cab's with a smaller surface area against the leg.
The more you tighten the legs, the more you seem to be pulling the wedge piece of wood against the corner joint from behind.
Factor in nudging & the legs being spaced away from the cab can put more torque/twist on the smaller surface area.

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Never seen a B/W pinball with those standoffs? Do JJP,CGC use plastic or metal standoffs? It may have been when Stern went to the plastic standoffs, AC/DC had metal, never seen a spit AC/DC cab.