Different attributes give different advantages when it comes to different styles. In striking, height and reach gives a huge advantage, but only if the person knows how to use it. Place two people that are equal in everything except reach, and the person with the longer reach is more likely to win. This difference becomes highly significant when both individuals are skilled.
In grappling, the shorter individual has the advantage by having a lower center of gravity. This results in them being more sturdy and balanced than a lankier person, provided that they are the same weight. For lanky and skinny individuals, the worst thing that can happen is being grabbed by someone shorter that isn’t too light.