Well their 'shitfix' is necessary for mp3s due to mp3s being a shitty format. It doesn't pertain to other formats most likely, but Winamp has always been primarily focused on mp3s.
mp3s always have a short gap at the beginning and end of 'em. When you loop it, it is very noticeable. To avoid it you need to wither do some 'correction' in the way of stripping out the silence, or implementing a buffer and db monitor which is obviously a much more beneficial route to take because it open up the way for simple cross-fading for those that like that.