This is total bullshit, and dangerous at that.
Firstly, a lot of software out there still has password length limits, sometimes silently discarding additional characters. You will still need ordinary passwords now and then.
Secondly, no normal human will type a five, six or more words passphrase every time they want to unlock their screen. They will do it for three days while they're hyped on how secure they are now, and then it'll become something they hate, and then they'll change it back to "123".
Thirdly, this is a bit more tricky, the real world security of almost every password scheme I've come across in 15 years of IT security experience is several orders of magnitude lower than the mathematical assumption. Because we consistently forget to take the human factor into account. Maybe some extreme nerds will actually follow this guideline, more normal people will discard words they can't remember for words they can, change things "a little" for convenience, and generally sabotage the whole system without even realizing it. It's the same as with passwords, all over again. Yes, on paper, a password has on the order of 10^16 possible combinations. But in reality, taking into account how people actually choose passwords (even ignoring the whole "password" and "123456" problem!) the actual diversity is more on the order of 10^9. Same here. You think using dice removes the human factor. omg do you underestimate humans!