In my experience the problem is one of listening. Duriong the early 20th century the speed of change in the evolution of new music speeded up enormously; compare 'Ein Heldenleben' , which was state of the art in 1898, with Schoenberg's 'Five Pieces' iop.16, of only ten years later.
But the habit of active listening suffered a decline, largely due to the introoduction of replayable recorded music, the 'I can listen to it later' syndrome. Few eol nowadats listen withbthe intensity that they did before recordings came along.
If you do (and I did 30 years ago when I discovered Webern) then it is not 'difficult ' at all. All you need to do is put aside yuor preconceptiions about what musuc ouggh to siound like and tell yourself to lsten to what you hear, with an open mind,a dn see what you make of it.
You will need to concentrate, but, believe me, it's worth it. My life has ben enrigched byu listening to the later works of Boulez, such a s 'Repons' 'Sur Incises' and '...explosante-fixe...', and by the symphonies of Per Norgaard.