This is a technique called loop unrolling. It is done for performance reasons. This is something we used to do at a company working on games for the old feature phones (think Nokia 30/40/60 series stuff). The devices were very limited, there is no direct control over J2ME garbage collection, etc... so loops could very noticeably slow down games.

We initially wrote code with loops, then would performance test and manually unroll when it was necessary. Eventually this became very burdensome and we eventually... wrote code to unroll the loops for us and that code of course had loops in it because it was build code that wouldn't ship.

There are other performance situations where this technique applies.

This may not have been the situation there, but I think it's important that rather than assume stupidity from the outside that we try to ask why.