But where is the fun in that? Seriously though, if the founding fathers had the ability to block people, there would be no bill of rights etc... Vigorous debate is good for society. It helps us evolve as a whole.
Currently I am "on probation" because someone flagged me as I disagreed with their meme and he called me a troll along with 3 others for saying so. Honestly I do not consider myself a troll, I may disagree with you, but I will cite sources and I have been known to come around sometimes. I have many users on here thank me for a vigorous debate, and I think that says something. I picture a troll as someone who just wants to attack you constantly, instead of discussing the topics at hand, but thats just imho.
If people can start blocking people, I think those that get butthurt easily, like the person who flagged me, sadly would abuse it and then IMGFLIP would basically become a hangout for only those who agree with you, which I think is very unamerican.