To elaborate, my definition of concept here isnt a simple "Why marine marauder medevac beats normal gateway units" or "why hellion banshee is so strong vs zerg" type of thing, but more of a "Why bomber chooses to 5 rax SCV all in ~14 minutes into a TvP" and "Why MKP doesnt like using ghosts"
To go a bit into both, Bomber's question can of course be answered with a simple "because late game TvP is bullshit" type of reply, but if we really go into the concept behind it - Late game bio TvP becomes a game of hide and seek with ghosts into sudden death, with the protoss having multiple lives (due to warp tech) while the terran only has one, in addition with ghosts being rather useless units other than for EMP purposes....
For MKPs question its even more simpler. He's MKP. Hes known for his insane micro, and he knows this himself. So while bomber opts for a timing attack, MKP bypasses that and chooses to attack all the time if he is able to, snowballing the game into a point where he can choose to power through the protoss army, regardless of storms, with or without scvs. For his style, ghosts will hinder his attacking force greatly as they do not provide the speed and dps, and simply costs too much barracks time and money to be worth using. If he doesnt manage to control the game, he usually loses because hes lost too many units due to his own mistakes or opponents play to be able to come back.
This kind of concept simply doesnt apply to the regular TLer, and to those in which such a concept does apply too, most of them already understand the concepts, making such a thread superfluous and not worth the time and effort to input.
Concepts like these create the meta-game, and the meta-game creates builds, and builds are which the usual TLer wants to read, although sometimes even builds do not really apply to the players because the level at which they are playing does NOT have a existing meta-game.
EDIT: To clarify, I do NOT consider myself as a decent player, due to only really knowing one race out of three (33% is still an F) and my ability flucuates too much for my skill level to be stable.