Economically: The cost/kill-reward ratio for AWP is several times bigger than almost every weapon in the game, which makes it economically hard to carry an AWP. In addition, an AWPer typically consumes 6.5K-7K Dollars of team investment, which means that losing an AWP hurts the team economy a lot, and buying one is not easy.
Mechnically: There are several shortcomings with an AWP too. People often complain about angle-holding, but fail to realize that with an AWP, you literally have to hit the shot in 1 attempt, on the upper body. Unlike a rifle, where you can adjust the aim, tap and spray, even drag a spray and spam, you can't do anything like that with an AWP. You can't take multiple people on at once with an AWP, cuz even if you hit the first shot, you'd be immediately traded before you can reload another bullet. If you miss a shot, you're dead in an aggressive fight - you won't get a chance to adjust/reload. Because of this, AWP becomes almost useless in site-retakes by CTs. And similarly on T-side, you can't hard entry consistently with an AWP (you can do it with almost every other weapon).
Meta: Yes, this is the only thing that makes the AWP somewhat overpowered to farm stats. Unlike the past aggressive AWPers like FalleN/s1mple/JW/kennyS, etc, when Astralis reinvented the way CS was played, everything changed. We moved from a more aggressive mechnical skilled - CS, to a cold and calculated, percentage-based, heavy stratting and anti-stratting based, heavily tactical and timings oriented CS. They were the first to introduce the "angle-holding" and "save meta" (savestralis meme). Some CIS teams took that to the next level. sh1ro and Jame are one side of that.