It's a dark pattern because the usual reason is to be able to gather more data from the user, and to limit user control. By that notion I would say any design decision that helps the company while harming the user is a dark pattern.
When the "app" in question is essentially a less accessible web page, then I think it's safe to assume something shady is going on.
To be clear, I'm mostly talking about apps that are just a collection of views for a remote API. The only valid reason I can think of for these kinds of apps is because you're an ios/android developer and you're not good at making webpages. In that case, the best tool is the one you know.
iOS apps that use system controls generally have far better accessibility than web pages do, indeed accessibility is a primary reason for creating a native app.
I only have some anecdotal data on this one, and maybe I'm comparing to apps that are not using system controls.
My mother struggles with any ios App because of how the zoom is implemented in the different apps. She can get by with the built in magnifier tool, but only when she already knows the app well.
Personally, I recently had nerve damage in my hands, and it was very difficult for me to enter text. There were many times in native apps where it would have been much better for me to copy/paste random text on the screen, but I was not able to. I know that some web developers like to try to block that too, but I would also consider that a dark pattern.
Yeah - I’m sure that would have been useful for you, but it doesn’t really compare to the wide array of accessibility options that exist across the system.
Also copying a pasting working across all text is often an anti-feature for accessibility too depending on what condition you are working with. For people who have trouble with fine motor control, it’s much easier to have only the content text selectable and not the controls.
There is no one-size fits all accessibility solution.
This seems to be a good argument for an accessibility option to make all text selectable, and nothing to do with dark patterns.
If they really don’t want people to use it on the web they should simply turn down the web site and tell people to use the app or GTFO. Instead they keep it up but cripple it and then repeatedly beg the user to something they clearly don’t want to do.