User blog comment:VickyC/Intro to Wikia’s Development Process/@comment-13301-20111012175925

The image you just posted, namely, does explain very well why every new update adds new bugs. As you can see, those 3 gears are blocking each other's movement, resulting in a cool image look but completely non-functional product. This may be relevant also for the sort of new features we're getting, like the new message wall thing, with all the problems it's going to introduce once it's forced wikia-wide.

From the comments you would see on other staff's blogs, the team in charge of fixing bugs on wikia or adding necessary adjustements to new products to make then usable are far from light, agile, and iterative as you mentioned. You can see examples of reports of new bugs on every update, and I've also seen people reminding staff about the pending changes for the Rich Text Editor that Staff promised they would add/change/improve but no new change was made once it was released. I can't find that specific comment now because of the nature of the blog system that prevents using external search engines or see all the comments in one view.