You both make good points, and it's definitely true that advances and trends in the industry lead to diverse ride lineups. However, it's worth noting that parks that build these lineups set a sort of standard for other parks to follow.
Take the B&M invert for example. During the 90s, tons of these things were built at parks around the world. The large number of inverts from that time period are a product of inverted coasters being popular. However, since they have become so widespread, they are now a staple of large amusement parks everywhere. Parks that didn't gain one during this period are still building them today. King's Island lacked an inverted coaster, so they filled this "gap" in their lineup with Banshee. SFFT built Goliath in 2008. Inverts weren't the super popular ride type at the time they were built, but they were added to these parks to help round out their lineups in an area they lacked.
You could say similar things about hyper coasters. The largest number of hyper coasters built was probably the late 90s and early 2000s, when the ride type was a very popular thing to build. They're not a common project these days, but some parks (such as KI and Carowinds) have added them in recent years to round out the park lineups.
Actually, 3 of the last 4 B&M hypers built have been at Cedar Fair parks. I interpret this as a push to get their ride lineups up to par with their competitors that built this type of ride years ago.
So while it's true that whatever the new and popular ride types are can create diverse lineups, these lineups set a standard for other parks to follow. Not necessarily a magic checklist, but definitely some guidelines of what a good lineup can contain.
steel said:
If this line-up is somehow standard for competitive parks, how do you explain Europa Park? Alton Towers? Thorpe Park? Port Aventura? Disney? Dollywood? Either Busch Gardens? Six Flags Great America? Six Flags Great Adventure? Six Flags Over Texas? Canada's Wonderland?
A lot of those parks are located in Europe. While they certainly are highly regarded parks, they really don't seem relevant in the discussion of how a standard coaster lineup makes a large theme park competitive in the US. Alton Towers has pretty much zero direct competition with Carowinds as far as I can tell.
The discussion of lineups really applies to large parks that focus on rides rather than theme. Disney's coaster lineup is pretty irrelevant, given that most guests are focused on theming and/or the family experience. I'd put the same argument into Dollywood, where the beauty and immersive experience of the park seem more important than a massive ride lineup.
Busch has always seemed to be a healthy medium of coasters and theming. While their lineups are small compared to some other parks, the coasters they have definitely fit into the "standard lineup" (with the dive machines being something of a signature ride).
The last four parks all have large ride lineups, and while they don't necessarily check every box on the "magical checklist," they certainly cover a lot of it. I don't think anyone's claiming that this type of list is the be-all end-all of coaster construction, but it can certainly be applied to large chain parks that focus on large coaster lineups.