Waterfox has historically tried to maintain functionality that Mozilla isn't interested in maintaining -- and coming out months or years later giving up on those efforts. The issue there seems to be that the company that they had sold to wasn't making enough money to justify increased investment (or they just didn't care). If maintenance is going to struggle by moving away from Mozilla, I don't get the point.
With LibreWolf, I just don't agree with their choices. My own take on web privacy is mostly aligned with Mozilla's -- you can read my tutorial if you like - better privacy by default, but without breaking pages. I'm generally not interested in breaking pages, and I don't think most other people are either.