Well here's a counterpoint: I've been here since 2009, and I rarely frequent the military threads because I find them too technical and inaccessible to those without sufficient knowledge. I'm sure I'm not the only one who feels that way.
Is it a bad thing to post captions that make the pictures more accessible to the common reader? In the example you posted above, I wouldn't know why that guy was shining a flashlight under the plane. I also wouldn't immediately know why that plane has a parachute behind it. To you, those captions might be useless, but to me they're meaningful.
But if not again faked, two digit numbers with in the 2x2x pattern are from the Shijiazhuang FA - and here the 2nd Training Brigade at Yongji. This unit was so far flying J-7B/JJ-7A. May I ask why this is connected / related to Siping? Siping would be the 31st Air Brigade, a JH-7A unit with...www.sinodefenceforum.com
I really have no idea what Siege and Deino are talking about in the above post, or why Siege posted that plane picture. What am I supposed to see in that picture? I have no clue.
In contrast, I can follow @xyqq 's post, I know that those are pictures of the J-10A, and they're doing some night training. That is meaningful to me.
I would suggest to ask questions if you're curious about something. There's nothing wrong with asking questions; in fact, it's highly encouraged in the military forums, provided the questions aren't unhelpful one-liners. We even have a "ask anything" thread for each sub-forum for more general technical questions. I've always made a point in answering them when I can.
Again, the specific point here is knowing when and when not to add a caption, especially when a concise overall summary would do just fine. That specific post you mentioned, xyqq actually didn't explain why the ground crew member was shining a flashlight. Moreover, I think most certainly you can tell when a plane is taking off or landing, especially at night when the engine exhaust is far more visible, or when it's simply taxiing on a runway or making its way to the hangar. So something along the lines of "so and so participate in a night exercise. Note the construction number in the first image" would be more than sufficient, assuming these uninteresting and low-quality images deserved to be shared in the first place.
To me, his posting style just gets old after a while. It's like sitting through a boring relative's slideshows on her boring, umpteenth trip to the local flea market, with each mundane slide described in mind-numbing detail. Yes, I can tell that's a moldy old sweater being sold for $1.99, I can see the price tag; the same for the dusty desk lamp, because I know what a desk lamp is; and yes, I've noticed the said lamp is the third item from the left, after a garden gnome and a bicycle. Yes, I know what a gnome and a bicycle are, and so on and on.