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.