Most of the problem is that passwords are either easy for computers to crack or hard for humans to remember. The middle ground has disappeared as computational power has increased.
Obligatory xkcd comic: https://xkcd.com/936/
Although mathematically the password given in the comic has a higher entropy and would take more time to crack under normal circumstances, the problem is that it follows a very simple and easily describable pattern: smash (four) dictionary words together into a combination.
Crackers will simply start using wordlist rules to generate large lists of meshed together dictionary words and use them if they have good reason to believe you're using this pattern (pretty sure it's simple with tools like Crunch). Whether they'll guess the proper order is unknown, but as with any other case people will use certain permutations and combinations more than others.
$ wc -l /usr/share/dict/words
119095
$ python -c 'print(119095 ** 4)'
201175048646341950625
$ python -c 'print(85 ** 10)'
19687440434072265625
So even if it becomes known, it's an improvement on what users are doing now.
Obviously a random 64 character string would beat either of them, but if you're expecting a human to memorize a password, correct horse battery staple is clearly preferable.
There are more possible permutations of four words than permutations of 10 upper/lowercase letters, digits, and common symbols. The four random word approach is harder to crack.
Create a near-random 63 char password, put it in a text file on a USB key and possibly print it out as a QR code and you’ll never have to worry about either entering it by hand or it getting cracked by that strange kid across the street.
is a really good password that people can remember easily.