I think it’s because there are important, naturally occuring units of time that simply don’t divide well - that is, the day and the year. Having it standardized to metric would still leave us with 1:365.24 conversion. Using metric time would require us to stop being metric beyond the day, or just have a cumbersome conversion number to talk about years.
On the other hand, things like weight, length, and temperature are completely arbitrary and there’s no natural standard unit, so changing those to another completely arbitrary unit is easy.
Maybe they should feed back the results that keep the scammers connected the longest, so it can learn from its own examples to waste the maximum amount of time
That’s the same argument for (some) Imperial measurements, but people converted to metric anyways.