They lose local logs which are crucial if you run into weird problems - whatever went into the dashboard, will stay there obviously, but its only what you see in it (not much of value).
I had a few times issues that would turn the whole network unusable and in the end I rebooted the devices and everything went back to normal (matter of ~5 minutes).
When I created a case after that - 99% of the time support would say that the switches loose all logs and if I run into issues I should call support so they can grab the logs and then eventually reboot the devices (which means hanging in the support queue in extreme cases up to 20-30min.)