I mean, if you are already know you’re using GCC, knowing to browse the manpage for info is easier.
The problem with manpages is, in my experience, they are vastly ill-suited for the “modern” / desktop-like workflow of the distros. They’re point is they’re not the tool for that, they are reference manuals focused on the tool, not training pamphlets focused on the use. Like, what is the manpage for “my desktop icons disappeared”? Even assuming there’s one. Or for “my desktop is in Italian but my start menu is in Swahili”? Or for “after video driver update and reboot my screen is monochrome”? Heck, for most of those even figuring out a proper info page (the “competitor” of man page) would be next to impossible.
So, there is of course merit to reading the documentation. But for that someone has to first isolate the workflow and write that documentation. I’m not interested in the man page for “steel” or for “lacrimals”; I need the usage pamphlet for “Slicing onions with a kitchen knife”.