'•The team liked giving classes time to shine in Uldir that didn't necessarily involve damage, such as mobile classes in the G'huun fight. They then realized that people just stacked Warlocks for it, and kind of negated the original intent, though Warlocks got to shine!''
Well yeah, that's the inherent issue with the 'strengths and weaknesses' class design. Making encounters that only certain specs are good at will mean you stack that spec. If they are trying to avoid class stacking they are not addressing the root cause, which is gutting most specs' toolkits.