It’s raid rebuild times.
The bigger the drive, the longer the time.
The longer the time, the more likely the rebuild will fail.
That said, modern raid is much more robust against this kind of fault, but still: if you have one parity drive, one dead drive, and a raid rebuild, if you lose another drive you’re fucked.
And frankly, even if he’s not a facist himself, the CEO saying something that fucking stupid makes me think that you shouldn’t trust him to run the slurpee machine at a 7-11, let alone something sensitive like your email.