Hersheypark's in the same place - I think you have a problem where the park is just not "known" for shows anymore like [Dollywood, SDC, Fiesta Texas, Busch Gardens, etc]. And there's no real push to keep that going, even to try to win industry awards. I'm not sure it would find an audience in these parks who wants to watch shows over riding rides, without spending a lot to develop and promote a whole new roster of shows (it likely would not happen all at once but over several seasons - something I think parks are not looking to do without a faster return).
Probably better to invest in some open-air stages near restaurants or paved pathways where you can bring in live musicians. I could picture a piano player in the Western area, and maybe some kind of live-singing street show around the entrance. It really would not take much to bring a little bit back, over time.
My home park, Six Flags Over Texas also suffers from a recent lack of live entertainment (outside of the holiday seasonals). The Music Mill Amphitheatre in the back sits as a reminder of a pre-Internet, pre-Ticketmaster, pre-pandemic era when the idea of visiting a theme/amusement park for concerts still made sense. Now the venue exists either for (a) the occasional school band competition or (b) storage and preventing further damage to the adjacent creek's flood reinforcements. The other theaters have fared a bit better, but locations like Crazy Horse Saloon and the Majestic Theater basically only got significant use during Fright Fest.
I also think park management's figured it's a better bet to do pop-ups and to center entertainers at the park gate and a bit beyond. Viva la Fiesta actually did a decent job having persistent showtimes for mariachi dancers by the gondola in the Mexico area this year. They should consider doing more IP-based small shows at existing open spots in Gotham and the corner by the kids area and the USA midway (or in front of Justice League BfM). Worst case, further rework Star Mall's front garden into an open theater space, add some foldable bleachers, and put more of the medium-sized events in there. (You can always relocate foliage!) At least the park's kept its props and costuming departments after all this time, so it's easier to supply temporary/permanent entertainers and staff than elsewhere.
I do think there is DEFINITELY something to what
@paintervision is saying though. So many parks have eroded away any expectation of quality entertainment from the park experience over the course of decades now. I do think that has been to their detriment (narrowing of the parks' target audiences, reduction in repeat visitation to see short-run entertainment products, reduction in activities on non-weather-optimal days, loss of an entire type of less-costly-to-debut attraction, etc), but I don't know if we'll ever see the glory days of park entertainment return again now. For it to happen, it would take a park with a very long-term vision who is willing to endure many, many years of suboptimal investment into entertainment products on the hope that they could reignite the regional demand for those products. The likelihood that anyone will tackle that seems slim, sadly.
Yeah, even considering labor costs, bringing guests in via consistently fun, humorous, and/or exciting shows is still less risky than burning millions on a potential misfire of a ride. I wouldn't count on being able to sway many renaissance fair fans in a year or two, yet there's a lot to learn from those and similar events who can build communities around local crafts, better food, and a variety of performers who aren't just targeting the LCD. Selling this angle to investors and corporate would probably be a nightmare now, with or without anything as disruptive as COVID. But all these things would go a long way to eat some guests' attention, justify more indoor space use, and add generational variety back into the parks without as big a capex splurge.
If you can't enjoy sitting down to eat near a musician by full(er) service dining, or organically stumble into an inviting show space (via loud signage of course), then the "park" part of the value proposition can fade too much. Social media clips and Bandcamp don't have to usurp the real thing if done right. I think non-ride, non-game entertainment should remain relevant to overall labor, dining, and infrastructure upgrades at regional parks in chains like SF. The main problem is how to start and sustain from first principles, avoiding the "didn't work in one year, off with its head" problem that Cedar Point faced with Forbidden Frontier (vs. the decent amount of midway stunt and dance events they're good about). Hell, I'd take a kid-friendly improv comedy show if that's the level of spendthrift some parks would need to set some momentum