I think this should be retitled to "The sorry state of OpenSSL usability [on macOS]", because the author is using the built-in OpenSSL on macOS (which, as is eventually discovered, isn't actually OpenSSL). If you want to use OpenSSL on macOS, I suggest using the OpenSSL provided either in Brew or in MacPorts. That will give you a fully-functional setup (including help and man pages).
Outside of the man page issue all of the complaints from the author apply to all platforms that have openssl.
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 19.04
Release: 19.04
Codename: disco
$ openssl --help
Invalid command '--help'; type "help" for a list.
$ openssl help 2>&1 | head -n 3
Standard commands
asn1parse ca ciphers cms
crl crl2pkcs7 dgst dhparam
$ openssl help asn1parse
Usage: asn1parse [options]
Valid options are:
-help Display this summary
-inform PEM|DER input format - one of DER PEM
-in infile input file
-out outfile output file (output format is always DER)
-i indents the output
$ openssl genrsa -out foo.pem
Generating RSA private key, 2048 bit long modulus (2 primes)
......................................................+++++
.......................+++++
e is 65537 (0x010001)