The knowledge of what ip address correlates to some hostname is just data like any other data. There is nothing magically specially different about it, and no way to differentiate it from any other random data that every single process processes.
It's a meaninless wish for something that you can't have, that we all agree would be nice, but is silly to expect.
An app can simply include it's own hard coded list of ips if it wants, or some totally home grown method for resolving a name to a number from any source. It's just key=value like all the infinite other data that every app processes. normal dns and doh are nothing but standards and conveniences, they don't actually control or dictate anything.
You wish apps couldn't do that? So what? Do you also want a pony?
