As they would say in 13th-century France, Mauves ouvriers ne trovera ja bon hostill. Or as literally translated, "A bad workman will never find a good tool."

The complainants against tubeless are relatively few, but boy are they ever vocal. I have over 8,000 miles (this year) on Maxxis ReFuse TR tubeless, with absolutely zero complaints. They mount/dismount easily, last 3,000-3,500 miles per rear and 5,000+ on the front, and I have recorded zero flats in those miles (by contrast, due to a low-stock issue I spent about 2,500 miles on Michelin Pro4 Endurance, and recorded 4 flats in that period.) By the time a rear tire is worn out, it has more holes than a pincushion, but has never gone flat, or even so much as lost an amount of pressure requiring me to add more air.

Now on the other hand, if my only experience with tubeless had been the Schwalbe One, I would probably be a vocal dissenter as well. There are good and bad tubeless tires out there, just like there are good and bad tubed tires. But some people will complain about any old thing.