I must've dreamed up the dozens of times I did.
Unless you mean you still need JS to build the modal, which is true but I doubt GP was implying that you shouldn't use JS whatsoever. You don't need a SPA to build a modal.
If you know in advance that you will never have complicated combinations of states, then sure, go ahead and use alpine (vanilla DOM element creation makes very unreadable code) or if you won't even need to create elements don't use anything... but the situations where you really know your application won't evolve that way are very rare next to the situations where you merely don't yet know that it will.