Yes, Wavlake publish RSS to the index (which is great) but they don't show any external RSS content within the Wavlake app (which kinda sucks).
In this context though, it's mostly that Wavlake is a middleman so no direct payment to artists via RSS like @Amplified Tunes mentioned above.
I thought that might have been what your comment was about but I maybe I got it wrong? If so, sorry for the confusion.