Universal has a bizarre "announce as late as we can" policy after the 2009 downturn in attendance because people delayed their trips to 2010 for the opening of Potter. In my opinion, those claims are a tad exaggerated as Universal hadn't built many things before that. Only The Simpsons in 2008 and Mummy in 2005 before that. Mummy was a great addition but started a trend of thrill/motion rides that replaced more family-friendly (no height requirements) options at the park.
Universal's target audience, at that time, was the older crowd as they just couldn't compete with Disney in the children/family market. That's obviously changed now, hoping that Epic starts a trend of going back to basics by creating attractions that are family-friendly.
I don't agree with Universal's current marketing strategies, but they have some severe nightmares that still linger from the openings of USF in 1990, Hogsmeade in 2010, and even Volcano Bay in 2017. IOA opened fine, but partly cause nobody showed up due to the 'Escape' marketing failure.
Universal hasn't had a successful park opening in Orlando. Universal is considering blocking/not selling APs that include Epic for the first few months of its public opening, so it might be a 4th failure. We'll see lol