The @bitcube account has been idle since 2016, and that happened suddenly without notice (prior to going offline, there was active engagement). There was a theory circulated that the person behind it may have died without giving anyone the keys, but I have no idea if that is true.
The @mottler account was inactive since the start of the Steem chain (never engaged to my knowledge) before recently powering down.
It is actually not true, bitcube is alive and he left the crypto space. I have talked with him last year regarding this matter at first he talked, but after that never replied nor saw my messages.
That's good to know, thanks! No one was able to connect with him back then.
Mottler surprised some people around here :)
Any info about the safari account?
Not familiar with it.