Most of us grow palms for their aesthetic value and for me and many of us, dried up brown persistent fronds are a detriment to that. A lush green garden versus one that has lots of dead hanging foliage, hmm, which one do I want to look at and be in? Fortunately most of my palms are self cleaning but many, such as Parajubaea, Livistona, Syagrus, Trachycarpus, Phoenix, and others are not so I trim off yellowed leaves. Rhopalostylis, on the other hand, often shed their oldest frond while still green and quite heavy. The stems and old boots of virtually all the palms that are trimmed here, fall off readily, many right up near the palm’s canopies with just a few exceptions. I don’t think leaving the dead fronds hastens trunk “cleaning” appreciably.