You're essentially arguing that amateur work is professional because it serves a professional purpose. I can get my brother's nephew's cousin who took a design class once to make me a flyer but that doesn't make it professional. Even if I use it to market my business, that in itself doesn't make it professional. Professional work is done by a pro, not by someone who downloaded a program, dropped in some clip art and spent 10 minutes trying to decide between Papyrus or Comic Sans for the text.
All the examples you've given can be done in MS Word, just like html pages can be built in word. That doesn't mean Word is good enough for 99% of actual professional design work, much like GIMP isn't either.