You say it's "yeesh," but I know that I personally won't respond to a wall of quotes or will ask the person who made the response to summarize key points from their post. It's easier to read small paragraphs, but fisking tends to create far more scattered text that is divorced or removed from its original context, which becomes an issue when discussing things in a forum, where it can be difficult to follow the flow of conversations through quotes. This is one reason why fisking is considered poor form in online discussion in particular.
Moreover, it's far more difficult to respond to a whole bunch of selective quotes than a smaller set of quotes, and it tends to lead to even more walls of selective quotes. It's also usually a sign, again IME, that the conversation has broken down. It becomes less of a conversation and more of a line-by-line argument that drifts into tangents about the fine points rather than the whole.
And again, its rejecting a response not on content but on form, which isn't fair to the person responding, especially when you're asserting without evidence that just by doing it in a particular way that context is being ignored or warped.
Personally I find the ease at which fisking is being thrown around as a bad thing to be rather shallow; as though one has read that its a bad thing and internalized it, but without any real understanding of why and how.
And its also good to note that not everything in a post needs a direct response or even a response at all.
Some things can simply be left undisputed or unspoken because they simply aren't anything the responder disagrees with or cares to comment on.