At a certain point, it becomes more of a "death by a thousand cuts", though. TTs not being in the road cup isn't a major factor, but it is
a factor. Same with inconsistent Merckx TT rules, lack of stage races to apply TT skills, niche equipment, etc. None of them are major factors in and of themselves, but they all add up. I know I'm in the minority of people that actually enjoy TTs, but for those that aren't in that boat, the current environment doesn't give much incentive to jump into the discipline.