Is this question on topic on unix.se.com:
what's the application/use of unifying the two API[console API and file API] and providing such a feature[copy file from one terminal to another]?
I think it's fine, although I would definitely explain the whole context in the question. Something like:
It was explained in this Stack Overflow thread that each logical terminal has a "pseudo-terminal", and that writing to one:
$ cat some-file.txt > /dev/ttys002
will cause the data to appear in that terminal window. What's the reason for providing a file-like API to terminal windows? Is there any use case where this is helpful?