Linux derives from Unix, and Unix has always used \n without carriage return (citation needed). And "always" in this case includes the time were there weren't any screens yet and you actually had to print everything out via a teletype (automated typewriter). They probably figured that you would never want to do a carriage return without a line feed (or vice versa), or that shenanigans like boldening a line by only doing a carriage return and printing the line a second time* should not be baked into the structure of text files which are a linear streams of bytes and supposed to be printed out as such.

And of course Unix predates windows by decades.

* extremely inefficient if you think about it for a minute, cause you have to store the entire line a second time. Better do it with syntax.
The other case where separating \n and \r could be interesting would be if you wanted to do intendation by linefeed (i.e. you keep your intendation level by not sending the carriage to the start of the line) but again, if you think about it for a minute, that doesn't work either.