yes I have never fully understood this, and I will keep it that way
Same here, never fully understood this days destroyed statistic.
Why it is important or it matters when old coins moves? What this tells us?
Old coins being moved = more coins in the market, because they were out of the market for some time and are not being dumped.
Also it is an indicator that people are not moving coins to themselves, or only to be dumped and have no effect in price
Its a purely statistical thing, its just something like the coin weight used, which is calculated by the coin age and size.
Basically if 10 BTC has been idle for 100 days and are then moved, it is going to equal to 1000 BTC days destroyed.
Imo its a statistic that hold very little interest for the majority of users.