Actually, I do know what I am doing. I have no idea the ratio of designer/photographer use of Photoshop. Whatever the ratio, it does not prove ease or efficiency of use. I use Photoshop, Illustrator, and InDesign regularly. That is the hazards of the profession--know what tool to use.
Never using Illustrator would be my choice. Cannot stand the programme. Clunky, clumsy and pointlessly difficult to use. Less dreadful than it used to be but still don't like it. Always preferred Corel Draw myself, but as it was a PC only programme it always got sneered at by graphic designers. Didn't stop Adobe borrowing lots of ideas from it though.
A lot of people use PS for design because even if you may not think so, it is actually very good for design as you have very precise control with pixel editing capability, painting tools, drawing tools, type tools, blending modes, layers....etc. I remember being puzzled at how many examples of really good graphic design were produced in Quark [what a crap/overpriced programme] some years back and then found out they were actually done in PS and whole page was then placed in the Quark layout. A good example of knowing what tools to use.
And as I said a couple of times above PS is not suited to long form layout, but graphic design is something it certainly excels at and is why it is often used to do web design, even if the coding and final layout is done in say Dreamweaver.