It seems to me you are only taking one part of the sentence to heart, the "too experimental" part. Seems to me that the "non-commercial" part is the most important one the publishers care about.
There are lots and lots of reasons publishers reject books that have nothing to do with the quality of the book and everything to do with marketing. Just as a lame example, if vampire novels are "in" right now, they'll snatch up more vampire novels, BUT if they already have the max number of vampire novels they think they can sell for the most profit, they'll reject your novel.
Experimental writing has happened for literally millennia. That's why we have the now-considered-traditional novel in the first place! And then the Modernists in the early 1900's were all about breaking all the rules, and then the Beats broke some more.
But note that most breaks with tradition happened gradually. They broke some rules, but kept others. Just like Jazz musicians. Because too much strangeness too quickly turns off too many readers. You might think that's a negative feature of humans. Maybe it is. But it's also just kinda a fact. We can deal with only so much unrelatable dissonance at once in writing or in music. In time we get used to it and it no longer seems so awful. Lots of chords we consider pleasant now, were considered totally dissonant in Mozart's time. You can't expect too much change from humanity too quickly.
But also bear in mind, that (just like with too much musical dissonance!) if you have too much experimentation that the reader is not used to, the whole novel no longer seems coherent from their point of view. You might see how it all works together, but they can't. Again, you can critique that... but if you consider that art, and especially novels, are meant to be a form of communication, you may want to take your audience more into consideration.
Also, here's a list of some famous books rejected many times before publication:
https://www.dailywritingtips.com/famous-books-rejected-multiple-times/
Rejection is hard, and it's harder with something you've poured much blood, sweat, and tears into. But it's also just part of the life of a writer or artist of any kind.