If you did not print it then you did not print it. If somebody else printed it then that's not your problem.
Literals, including strings, get ignored if they are not used, that means that sure, strings can be used as comments.
When placed in certain locations they become docstrings instead, they get associated with that module/class/function. You can for example print the docstring for
Most text editors intended for writing code support (de)commenting lines, there really isn't much need for the syntax supporting multi-line comments. (Fro example, in vim I might type the following to comment this and the following 4 lines:
0(ctrl+v)5jI#(ESC) That makes lots and lots of sense I'm sure :p)