Does someone know why ARM servers try to behave like intel servers. ARM's forte is in tons of lightweight cores, compared to intel's small number of powerfull

Does someone know why ARM servers try to behave like intel servers. ARM's forte is in tons of lightweight cores, compared to intel's small number of powerfull cores. There are tons of small mom n pop websites that have short burst of usages, followed by long bursts of calm. So why not give every site on a big server it's own small core, say for 60 seconds? After that you shut the core down, zapping all caches etc... Things like meltdown and spectre simply disappear if the attacking code runs on a different core, so such an architecture would be good at isolating security sensitive data. In these GDPR times, it seems a good match for small sites, and one that Intel can't provide with their good but power-hungry cores.