Kegan, Like Thimo said, It's primarily historical dogma spread by those with agendas, perhaps limited bow wood to use like only osage or yew, and the lack of knowledge/open mindedness to give other woods a legitimate shot...
Every environment has woods which will perform best "in general" Osage for example is good in humidity, and its humid where it grows, but take it to 100+ temps and sub zero/ very low mc%, and you are much better off with hickory, elm, guava..tension woods since your osage bow could very well end up in pieces with prolonged exposure. This many of us have seen first hand..
And most white woods don't do well in humid conditions..
its these variables which help those with "agendas" drive their "point" home as well. At mojam I picked up some fine elm, and osage since where I live is as near a perfect condition for bow woods as there is, and thus my signature elaborates this point..
They all work good, if you have a clue
Rich-