I am doing my best to talk to the owners of imgflip. Just because they have not removed the image yet does not make it right for you to use it.
If you were playing a recording of a local band for parties, and got asked to stop because it was a pirated recording that the band made no money off of, would you stop? The right thing to do would be to stop or to buy the legal recording. Do you disagree?

I am here advocating for the creator because I worry that the proliferation of credit-less copying will reduce the income stream for small-time artists & creators such that they no longer have time nor energy to create content. I certainly don't want the creators to have to waste their time fighting against illegal copies rather than creating more awesome content.

You can see that Allie Brosh used this image in a 2010 blog post if you look at http://hyperboleandahalf.blogspot.com/2010/06/this-is-why-ill-never-be-adult.html; the image used above is the 4th image on Brosh's blog post.
If you then continue scrolling down, you will see a copyright paragraph in the right-hand column; if you check out the Creative Commons license she used, you will see that it requires anyone using her images to give her credit. Therefore, using the image without giving credit is illegal, and also against the terms of imgflip.

I know that many people do not know the image is copyright -- that's why I try to educate. Once someone knows it is a copyrighted image, the right thing for them to do is to delete the image or follow the terms of the copyright.

You may be correct that imgflip will only listen to the copyright holder. That would be too bad, since that then means the copyright holder bears the burden of the time and energy required to try to remove illegal copies. It seems like it should be sufficient for someone else to show that the copies are in fact illegal.

"This isn't a copy written image." What do you base that statement on? If you look at
http://hyperboleandahalf.blogspot.com/2010/06/this-is-why-ill-never-be-adult.html, you will see the image used above is the 4th image on Allie Brosh's blog post. If you then continue scrolling down, you will see a copyright paragraph in the right-hand column; alternatively, if you go to the end and scroll up a bit, you will also see a copyright notice there.
If you check out the Creative Commons license she used, you will see that it requires anyone using her images to give her credit. Therefore, using the image without giving credit is illegal, and also against the terms of imgflip.

I have in fact been flagging as many images as I have time and energy for, asking imgflip to remove them for violation of terms of service.

I know that the image is everywhere. I know that many people do not know the image is copyright -- that's why I try to educate. Sometimes, my messages are not worded as well as others, but I do my best.
If pirated copies of a small-time band's latest CD were everywhere, it would still be illegal and wrong to make more copies. Same goes here. Once someone knows it is a copyrighted image, the right thing for them to do is to delete the image or follow the terms of the copyright.

I worry that the proliferation of credit-less copying will reduce the income stream for small-time artists & creators such that they no longer have time nor energy to create content.

I am not the owner, but I have indeed requested removal of the templates and memes that do not give credit.
I am sorry you see me as sanctimonious. I worry that the proliferation of credit-less copying will reduce the income stream for small-time artists & creators such that they no longer have time nor energy to create content.