For me I think the failure of the Haskell Prime effort to establish a successor standard to Haskell 98 was a big factor: the language and ecosystem became more chaotic and inconsistent over time as people drifted away from any hint of a common standard. Add to that the changes in the community when there were big changes in the cohort of “leaders” who had driven things from the 90s until the early 2010s (eg, when both Simons changed their roles). The folks who took their place haven’t done good things for the language in my opinion.