What. The. Fuck.
These people are obviously not writers themselves or they would know the reason that we write to begin with. We write because we are compelled to and because we want to offer someone else the chance to submerge into a world unlike their own, even if it's only for a short amount of time. And if those people respond to our writing, we write back to acknowledge them for acknowledging us. Getting feedback is the same as getting paid for what we're doing, so even when we get similar "oh this was great" or "how sweet," we still cherish it because they took the time to leave a message for us. And I respond to all my comments, even the short ones and yes, I do say 'thank you' over and over again, but it doesn't matter because it's important to me that my readers know that I read all of their comments carefully and cherish all of their feedback.
Any writer who thinks it's "cool" to not respond to feedback or any reader who judges an author's talent by his/her not responding to feedback obviously knows nothing about the written word and should not try to engage themselves into conversations where they've no friggin idea what they're talking about. And if you are a writer who thinks that you're cool cos you don't respond to your comments, then you need to GTFO of fandom, cos that's not what we're even writing for.