Maybe 30 years ago you could learn through manpages but today that's how all the man pages of all the useful commands look. If you think grep is nice it would be the exception; for me it is indeed short, simple and easily searchable, but too terse for a beginner to learn with easily. (Plus even the regex documentation only documents grep mode, not egrep or pgrep or anything else.) Very useful in its own way, but most man pages are useless for learning.
I am disappointed at how few man pages take the opportunity to have a useful selection of "the 10 most popular things to do with this command" but web search has filled in reasonably decently. You do still have to understand the basics of how shell works, though, because most of them aren't quite what you want today and honestly a fair number of them aren't even what the poster thought they were. I am also in the habit of making sure that I understand every command line switch before I copy & paste a command off the internet, again, because many of them aren't what you need today. I don't always mean in a malicious manner, but things like either do or do not follow HTTP redirects in curl may or may not matter to you today, but the poster may be in the habit of setting it one way or another for no reason relevant to you.