For reference, I’ve got measurement electronics manufacturing, testing, servicing and certification experience.
Cited expansion-contraction, as well as power-on-stress arguments are nothing more than myths spread mostly by Hifi journalists, generally being far from expert level in the respective field - chalk it up to prose.
Same goes for electronics burn-in to improve sound, btw.
Burn-in should actually be done by manufacturers to capture early failure outliers to not reach the customer - it’s a reliability thing, really.
I’ve personally conducted and witnessed certification testing where units, built with standard components, were stressed in extended thermal -20°C to +70°C cycling as well as power cycling tests - no wizardry or specialist components needed.
These units went into safety related installations to run maintenance free for 20 years in harsher than home audio environments.