Why do projects use the -I include switch given the dangers?

Question

Reading the fine print of the -I switch in GCC, I\'m rather shocked to find that using it on the command line overrides system includes. From the preprocessor docs

Answer 1

I this your premise that it's -I that's dangerous is false. The language leaves the search for header files with either form of #include sufficiently implementation-defined that it's unsafe to use header files that conflict with the names of the standard header files at all. Simply refrain from doing this.