You can, and I do, hope for this, and it's often what you get, but it's not at all guaranteed by the format. For example, PDF allows JavaScript: https://www.adobe.com/content/dam/acom/en/devnet/acrobat/pdf... . I think most readers other than Acrobat probably don't support it (which, of course, Adobe spins as a feature of Acrobat!), and not too many PDFs require it—although I do find that fillable PDFs, including from hopefully capable authors like the IRS, can be very finicky in anything other than Acrobat—but I fear it's only a matter of time until it becomes as difficult to "browse the PDF without JavaScript" as it currently is to browse the web without it.
> I don't want random authors to be able to dictate how I interact with a medium
On this score you're out of luck even now—if the author, intentionally or unintentionally, did a bad job creating the PDF, you're out of luck. This is one area where I'll give HTML the win: it is, or can be, good at things like dynamic reflow, whereas PDF not only isn't but, I believe, effectively can't be.