This is a legacy system requirement. We have some portions of our website written in PHP. Normally this wouldn't be an issue but at the time they decided to use PHP+Windows they were also trying to use MSSQL databases (All the microsoft influence was due to some azure credits the company received early on). The particular driver they ended up picking forced them into using the mssql_* functions instead of PDO. This meant that the majority of the site used these rather outdated calls and replacing them was a rather large endeavour. So while we migrate some of the PHP backend away to various node.js api systems we are simply sustaining the existing PHP portions. Microsoft IIS