I find this thinking bizarre. What matters is the simplicity of the API my code has to talk to.
You'd have a better argument if most people built their own terminals, like I have (mine is only ~2k lines of code, however), as then there'd be a reasonable argument you're writing that code anyway. But most people don't.
Even then I'd consider it fairly specious, because the terminal code is a one off cost to give every TUI application a simple, minimal API that also gives me the ability to display their UI on every computer system built in at least the last half a century.
I write plenty of code that requires more complex UI's too, and don't try to force those into a terminal, but I also would never consider building a more complex UI for an app that can be easily accommodated in a terminal.
You'd have a better argument if most people built their own terminals, like I have (mine is only ~2k lines of code, however), as then there'd be a reasonable argument you're writing that code anyway. But most people don't.
Even then I'd consider it fairly specious, because the terminal code is a one off cost to give every TUI application a simple, minimal API that also gives me the ability to display their UI on every computer system built in at least the last half a century.
I write plenty of code that requires more complex UI's too, and don't try to force those into a terminal, but I also would never consider building a more complex UI for an app that can be easily accommodated in a terminal.