@captaincranky, was you meaning too long horizontally?
Sort of, but not really. I'll be more precise, (or try to be).
With a 16:9 monitor in the horizontal, (landscape) orientation, the monitor is too short vertically, with respect to having enough height to display portraits effectively.
With a 16:9 monitor situated vertically, ("portrait" orientation), then it is too narrow, side to side, or horizontally if you prefer, to effectively display portraits either.
Run the aspect ratios of your standard size photo printing papers, 4 x 6, 5 x7, 8 x 10, 11 x 14, or even 16 x 20, which have been used for decades, and you'll see nobody has really been exposed to still images with an exaggerated narrow to long aspect ratio such as 16:9.
A small clue here, 16" x 20" is an almost square 4:5
I'll take an old fashioned 19" monitor, 1280 x 1050 (4:5) over a 19" "widescreen" 16:9 any day. You can't display an 8" x 10" portrait print full size, until you hit 23" in 16:9
Although granted, some photogs do goof around with ultra wide angle, even 360 degree landscape stitch me ups, gathered from multiple captures.
In the same way that a "one size fits all" Windows OS benefits nobody but M$, a 16:9 completely standardized aspect ratio, benefits no one but the panel manufacturers.
Even the most advanced digital capture sensors which are 16:9, are only used in conjunction with purely video cameras. Still camera sensors are still mostly in 35mm film aspect, @ 1.5:1 (A standard 35mm frame is 36 x 24mm).