Except for the fact that Qt is not as cross-platform as the standard C++ library. Qt also uses non-C++ features such as signals/slots which require usage of their own Meta Object Compiler.
Qt's moc is a preprocessor/code-generator which compiles to standard C++.
Do you also tell people that they shouldn't use flex/lex/bison/yacc/antlr/etc.? Why are those code generators/DSLs acceptable but the moc is not? It's not as if the Qt authors added it because they don't understand C++, they added it because it solves a vexing problem in C++ GUI design.
I would have agreed with you if Qt used something like the #pragma directive. Alas, they decided to inject keywords inside of the standard language which breaks every C++ compiler.
