New line without empty line between

When we want to make one-line break, we have to hit enter two times ( make empty line ).
I ( me ) suppose some knowledgable dev sit down and allow new line from ,… new line ( 1 time enter key )

the \ at the end of the line will make next one a new-line:

 this is line 1 \
 this is line 2

this is line 1
this is line 2