Smarty may have many limitation and drawback but many people, especially designers, find it very useful. Staying away you may miss out a set of valuable tools that help you build websites quickly and efficiently.
I’m not here to defend or promote smarty, nor I have never used it myself. But I know it is a popular system where many developers use it for their projects. Someone put together a list of such projects using smarty: http://smarty.incutio.com/?page=SoftwareUsingSmarty
I’m sure they all disagree with your assessment. If you can pull a semi with a pickup why spend extra to get a tow truck? A pickup will surely be more versatile; like taking it for a fishing trip. Do that with a tow truck and see how many people will be looking at you.
However, if you write up a more detailed article of why one should stay away from it then not only will it be helpful for people to make that choice but save them from wasting their time as well.