...it can be so disheartening for writers when there isn't a response to a fic they have been working on.

After all, a lot of time and effort is put into writing it out, into creating that story, so if you enjoyed even a little bit of it don't hesitate to let the writer know you did! One little comment, one upvote or subscription, it could mean just the world to a writer. 

I am speaking generally here. Feedback from the readers is just as important as the actual fanfics, I can't stress this enough. You can't expect someone to be willing to continue writing if there is no response to their works. You can't expect them to want to write after getting nothing that will replenish their will to do so. 

So please, it will cost you nothing to click one button or write a single word to cheer someone on, especially younger and new writers, people who just start out.

Encourage them and I promise, the results you'll get will be better than anything you might expect! :)