Why is it so hard to list proper technical specifications?

I never read user manuals, because they are usually a waste of time. The main reasons for me to read user manuals is because I need to check something that is not listed in the technical specifications.

A few weeks back I ranted about TV manufacturers unable to properly list their Inputs/Outputs in the specs and how I have to read the user manual to find out if I really am able to use it. Weirdly, some companies are unable to provide a shot from the back and a user manual.

My current reason to rant is the Acer B233HU monitor. I bought it more or less blindly because it has a resolution of 2048x1152 and because it has an HDMI input that supports that resolution (my graphics card can drive 3 monitors, but only has 2 DVI Ports, so I needed a HDMI or Display Port Monitor). Now I'm realizing how much space my monitors take up on my desk, so I remembered Jeff Atwood posting about Monitor Arms some time ago.

Now, to buy a Monitor Arm, I need to know the proper measurements for VESA Mounts. There is 75x75mm, 100x100mm and some other sizes. For my Philips 240BW that's no problem: Go to Philips website, look at specs, see that it's 100x100mm. But my Acer Monitor? No information. I can guess or measure myself that it's also 100x100mm (it is), but really, that belongs in the specs or the manual!

I think it's astounding that they list stuff like what the pins of the DVI Port do (As it's important for me to know that Pin 24 is DDC TMDS Clock-) but not what measurements their VESA Mount it.

Seriously, why is it so hard for companies to determine which specs are important and list them? Yes, I know that I belong to the minority of people who look at the specs and buy stuff that fits a need rather than just buying stuff because of bling-bling and advertising, but do you really need to constantly remind me of that fact? Can't you just - at least sometimes - pretend that us engineers are still valued customers?