This is true but they are often long and complicated and aren't always conducive to quick solutions or refreshing memories of a useful combination of arguments.
It is good to have both.
That's true. However I often encounter co-workers refusing to read man pages, because they only want to see a cheat sheet. They end up endlessly wandering Stack overflow and google for hours instead of spending 5 minutes going through the actual manual.
Sure, but some are very short, and others are very long and impenetrable. I like ones with examples. A better option is often "foo -h".
Also, the times a manpage contains examples seems like 1 in 20.
Especially in sections 2 and 3. Including examples would greatly increase their usefulness and I wonder why the authors don't do that.
those are hard to be considered cheat sheets... extensive reference documentation, maybe, but "command --help" is more similar to a cheat sheet than "man command"