Nearly 40 years ago when I learned to tie, we were taught to wax our thread as we went before tying flies. I think the wax makes the thread easier to handle, and I use several types of wax these days. I used only straight natural beeswax for many years.
Now, I have several blends, and they range from straight beeswax or parrafin, to some very sticky stuff I use for touch dubbing. I like wax, and use it all the time, but I ain't sure it's strictly necessary........that's my take, though I don't imagine it answers your question................................ModocDan