There is a problem of gradual imbalancing with that. If others were buffed, the balance would tip even more easily, balancing 3 to 1 is harder than 1 to 3. If any error would occur, they would again need to buff all of them, and then you're caught into a loop. Then new weapons would come, and all the buffing would be moot again. Adaptability is the 1# attribute an online player must have. Finding one thing and sticking with it doesn't work, because you subconsciously make calculations of the best gear, and often shift your playstyle accordingly. When everyone does this, eventually everyone who can use that one thing often will, and then it makes the playing field a question: "To be viable or to use the weapons that you really want to?"