I always stress to my students that they should memorize tabs and then alter, simplify, embellish, and otherwise forget the original!
The reason for memorization is to learn the technique as played by the artist / arranger of the piece. Once you have learned the techniques and insights offered by the tabs, then you can rearrange the piece and make it your own. It took me decades to develop and fully understand the techniques I regularly use while playing; my students understand and are comfortable with the same techniques after a few months. The difference is having a coach (me) and the techniques laid out in an organized and easily understood manner (tabs).
You can stumble around for years and try to discover the full spectrum of clawhammer banjo technique on your own, or you can utilize the wealth of materials available to the modern clawhammer student and speed up the whole process exponentially through the use of tabs.
This being said, it's equally important to be developing your arranging skills at the same time. A total dependence on either tab or your "ear" is not a good thing, you want a combination of both approaches.
Use tabs to learn Brush Skips, Alternate String Hammers and Pulls, 6/8 Time Technique, and other "advanced" techniques. After you have mastered the technique lessons found in every tab, then make the song your own by rearranging it to suit your own taste and style of play. Eventually you'll no longer need tabs arranged by others and will develop the ability to improvise your solos (arranging on the fly) when needed.
I use tabs to teach technique but my ultimate goal as a teacher is to guide my students to the point where they no longer need them and can effectively arrange tunes for themselves.
Just remember that there's a lot more to the banjo than just the "bum-ditty"...
Thanks... Mike