e.g. Photoshop can handle vector graphics on their own layers in conjunction with other pixel-based layers. Personally I'd still prefer to see a "flattened" file coming than a layered one (a lot of designers still forget to rasterize their fonts as they don't travel well), or know it was a flattened element within a PDF.
That's a loaded statement.
There are Smart Vectors - which are used by placing a vector in Photoshop - this means it can resized within photoshop without losing quality - however on export to any file format it's converted to a pixel image at the image resolution stated in the document.
Smart Vectors never output (unless printed from photoshop) as vectors. Ever.
Fonts are not designed to "travel" - in fact your fonts should be embedded in a PDF file rather than supplied.
The only file formats worthy for print from Photoshop are
PSD or TIFF for purely raster images.
PDF (saved with Photoshop compatibility so it can be opened in Photoshop and edited.
For this it would require also supplying the fonts.
The only vector elements that export to PDF from photoshop are Vector Shapes, Vector Masks and Text Layers.
And PDF is the preferrred file format for printers.
The two major areas that can still cause major graphic hassles for printing companies are font-related and transparency / overprint related. Everything else is pretty much sorted by the software these days.
If these companies haven't updated their technology in 20 years then that's their problem!
Fonts embedded correctly in PDF should be no hassle.
Transparencies and Overprint shouldn't be any hassle to a printer that has kept their business up to date.
However, I would like to add that it doesn't actually matter what you design it in anymore as long as you supply it in CMYK mode as a high-res PDF for the majority of non-spot ink/Pantone print work, most printing companies will be happy enough. We still love our Quark Xpress (v9.5 here with 10 sitting there in its early days of ongoing development) for everyday print work, design and file manipulation.
It's essential that the correct tools are used.
However, once the PDF passes the tests and prepress - essentially it doesn't matter.
But what does matter is future jobs. No point in designing 16 page document in Photoshop or Illustrator (yes I've seen it and worse try an 96 page magazine all individual tiff files!)
You can't really design a truly print ready and editable file for a client in Photoshop - it's completely irresponsible to begin with.
Photoshop for photos - clue in the title
Illustrator for Illustrations
InDesign for Design
yes there are other products like Gimp, Corel, Quark, Inkscape etc. but none of which are retaining compliability with modern print standards and workflows.
For graphics on Web pages, again if you can stretch to Photoshop, well it does everything and rules the roost, but if you want to just do a few graphics for web then Adobe's other little app from Macromedia's days called "Fireworks" also still does a decent job for the RGB environment. You can get it cheap on their Adobe CC subs set-up.
Photoshop is more for mainstream photos and editing.
Fireworks actually produces higher quality lower file size jpegs. It can also handle layered PNGs, and other things.
Fireworks is much better suited for web graphics and making buttons that work well with Dreamweaver and other things.
Fireworks is also Free not "cheap" with the Adobe CC - you sign up for Creative Cloud and all the Adobe tools are available for you to download.
There are also quite a few shareware apps out there that are okay at emulating what the big boys do, but really, in the professional world... Adobe rules.
Indeed - Adobe does rule the professional world.
Sorry for nit picking - but I simply don't agree with what you said on the most part.
I feel if people ask a question they need to understand there are caveats to going outside the box when designing, say choosing Photoshop over InDesign.
File Formats, resolution and other things really come into play when deciding.