Smarty was used well in old days. However, it became rarely used recently. Smarty has many advantages, but there are many faults at the same time, too. One of the advantages for me is cache feature. However, this can substitute in PHP. In addition, debug of smarty is inconvenient. It makes Smarty important to separate design and logic, but, except some exceptions, design and logic are isolated in Q2A. Therefore the further separation is unnecessary. The data structure of Q2A is very complicated unlike blog and general site. It will become really mysterious thing when we make template of Q2A in Smarty.