Here are some actual comments from a YouTube video that dismisses the value of Alternative Notations  (You can skip the first 10 minutes of this hour-long video since it adds nothing to the discussion of alternatives).  I believe that the position of the author is coming from the perspective of a replacement for Traditional Notation.  In my view, this should not be the goal of alternatives.  It should be to provide choices to players at any level of skill.   In any case, comments to this video reflect the challenge to promoters of them.

"I get mad when people balk at how much work it takes to learn to read sheet music or play an instrument. Of course it takes work! Everything else does, too!"

"[Traditional Notation] is easily accessible to anyone willing to let go of the preconditioned idea that note reading is too hard to learn. Far from being difficult, standard notation is the easiest thing under the sun and trying to replace it for lazy people and come up with over complicated substitutes is a complete waste of time."

"The challenges can be solved by tightening those bootstraps and doing something called learning."

"I spent half a lifetime struggling with the old system, AND SO SHALL YOU!!!"

"If you are an amateur, you can make up colors and symbols, but just learn to read music instead of being lazy."

"Conventional music notation is logical and is very easy to learn. People who think it's difficult were probably taught badly, or couldn't be bothered to work at it, or are a bit dim. I think it's a mistake to fix something which ain't broken just because a few dim people are dim."

"With all these new notation systems... it really comes to the conclusion that music is not for everyone! "

"it is what it is. it's what i've been reading for more than 40 years. leave it alone."

"I strongly believe that music notation is the most effective and efficient way to write, read, and analyze music. It has been developed through centuries of musical evolution and the contribution of numerous musical geniuses. In my opinion, it is not worth exploring other alternatives as it is the best compromise possible."

But then on the other hand there are interspersed these contradicting comments:

[Traditional Notation] "is inherently hard to learn. I feel like there HAS to be a better system than what current music notation offers, but I can't find it."

"I’ve played piano since I was seven years old, and while I’m quite used to sheet music notation, I still feel like a moron when sight reading something cold. Maybe I’m not alone."

"I play pedal steel guitar. I can read legit western music, but rarely do because TAB is most effective for this instrument."

"Notation was precisely why I gave up on any instrument as a kid because every time I had a motivation to learn, I was told that I had to learn the notation first, and then I could learn how to play. As a grown-up, I finally found a teacher who taught me how to play first and then to understand what I was playing by looking at notation."