Exactly. Remember, the initial headlines on the internet were pretty positive. Then when the score dropped lower and lower, the headlines became sour. People DO read that and DO make decisions based on that, especially in this day and age. The later the reviews come out, the better a potentially popular movie will do.
Fatigue is all fine and dandy but, for better or worse, the MCU is feeding the movie industry. If critics were less brutal to new properties, then maybe people would be more likely to make them and, more importantly, studios would be more willing to get them made. If all we can rely on is known superhero properties, then why bother to make anything new or take any chances?
So if it is true that the MCU is dominating the movie market, let's imagine what would happen if it was gone. What absolutely SUCKS is that critics will have jobs either way. They can continue to review movies and shows that nobody sees. But those hurt by low review scores are not so lucky. Feige will be fine, but award-winning Chloe Zhao may be shut out of big films. There are ways to critique movies without absolutely MURDERING movies that just aren't the best thing they've seen. It's really a shame.