Secondly by it's very nature and as made obvious by their name, extensions AREN'T standards, they are 'extensions' to existing standards, how can you fail to grasp that? And those who use these 'extensions' do so because they really feel they need what they offer, knowing full and well that there is no guaranteed compability across compiler toolchains given that they are NOT standards.
Also, you do realize that most of the features in later standards started as extensions and then elevated into standard functionality when they had proven their worth and stability?
In conclusion, both GCC, Clang/LLVM, Intel Compiler implements compiler _extensions_ which offer functionality beyond what the standards define. These _extensions_ are not supported across all compilers although some are, GCC has exclusively supported extensions, Clang/LLVM has exclusively supported extensions and same goes for ICC.
I find it hard to believe you are a programmer at all, you sound like a person who just compiles other people's code and throws a fit if it doesn't compile with *your* favourite compiler. And if you feel you have a legitimate reason to complain then you should take those complaints to the actual programmers who CHOSE to USE these extensions, not to the compiler vendors who make them available at the request of those same programmers. And you should certainly not single out GCC as some culprit, because all these compilers implement extensions and each with their own exclusive ones.