Do you actually have the sconnect or connect program installed? If not, then you need to find the package containing it or to compile it from source. Also when specified from the command line it should be -o ProxyCommand=“connect …”
That document is very old so take this with a grain of salt.
What happened is that HTTP and HTTPS became the most common used protocols and the generality of SOCKS wasn’t needed at those sites. So SOCKS fell into disuse. The main problem with SOCKS was the need to socksify apps. sysadmins got tired of retrofitting this support all the time.