Check out this funny little image Olof threw together! Something Paul has said a few times, there are just some things we say and talk about around here that rub people the wrong way, but it's usually because they just don't know what we're talking about!
I've used this expression a few dozen times. It seems that there are many times that somebody is being a troll and rather than trying to understand they are trying to NOT understand. And rather than get in a wrestling match with a tar baby, I choose to instead focus the conversation on those that are trying to understand. The idea is that I wish to share my ideas with people where we can collectively grow from the thought process, rather than stagnate growth by getting mired in tar.
A lot of times, the tar baby is a corporate troll - so this is a way to dodge the corporate troll.
Sometimes the tar baby is somebody that legitimately does not understand - so when the thought process gets further along, it would be wise to come back and provide a step-by-step tutorial.
But most of the time, it is somebody that is demanding to be spoon fed and carried into knowledge without trying. And I think this expression helps to get them to at least try to understand.