Слава Україні!

Героям слава!

But most people don't have such a good memory.

It's a matter of practice and repetition. If a person cannot memorize a long phrase from 1-2 times, then he will be able to memorize it from 10-1000 times. This is a matter of desire. If a person wants, he will find a way to memorize a long phrase, even consisting of random characters. Alternatively, in addition to the phrase, you can use some publicly available file as a key (billions of files are published on the Internet, the attacker does not know which one can be your keyfile).

And, if you've experienced a traumatic event, even your fantastic memory may be compromised.

OK, I can't offer a one-size-fits-all solution that will work in all cases. But at least the solution I proposed will work with the case described in your article (in most cases).

Of course, you remember exactly which capital letters you used, whether you replaced any letters with numbers, and if you used spaces or not?

Sure.

Wait... is it the same poem you and your friends all learned at school?

Maybe.

How long do you think it will take them to crack it?

40+ symbols including digits and capital letters. My passphrase consists not only of a line from a poem. I think it will take a very, very many years.