It's nuts that software developers are allowed to design user interfaces at all. They're incapable of making a user interface that isn't text. It's like if plumbers designed houses, they'd make all the floors slope downward, because that's the easiest way for pipes to run.
Oh we need multiple windows we can move around/resize? Let's make them text windows. We want people to be able to quickly select options? Yeah make those text boxes. We want to quickly compose documents with some kinda style/formatting? Yeah they'll need to write more text to format it (but let's not make any apps to easily view the text in formatted mode).
Allowed? Many if not most of these open source TUI projects were started by individuals or small teams who wanted to solve a problem for themselves.
It’s allowed. You don’t have to use them.