Cabinets are not really the issue.
Electronics and parts.
I have never seen a RS yet that did not have some sorts of playfield parts in the bottom of the cabinet over a period time.
Mostly nuts and mini light bulbs, but some of the driver boards also get busted up like the LED sign boards, and event the motor EMI driver boards.
Today's surface mounted boards conformal coatings are much better than the original component boards for protection, but solder traces and connections DO crack under the vibration.
I really don't know how well SPIKE boards have been properly tested, but a shaker motor is like lifting the machine up and down at high frequencies without dropping it.
Over time, high frequency vibrations do damage modern PCBs (those type of boards under high stress in other industries are normally independently mounted with shock absorbers which is not done in pinball machines), but the periods are longer than the lifecycles of the boards themselves that are only designed for roughly 5 years before failure.
That is something people may not know.
Stern is not designing these games to run forever.
They are designing them to run for under 10 years (commercial environment) and be replaced with new games.
The cabinet is not going to give out in 10 years, but the electronics may.
I cannot tell you the risks with CGC MMr and the master PCB under than playfield at half its overall dimensions with a shaker motor running, but it does not not favorable in terms of overall vibration antics.