Heh... I rank the term "By Design" and, especially, the term "Operates as Designed" right up there with other "lameties" (to coin a phrase and is similar to the well intentioned but still annoying "lame ties" that get hung around our necks on Father's day 😉 ) such as "We've always done it that way" and "We've never done it that way before".
As for the "Quirky Update", people use such things because they have a need and don't want to wait a day for a supported method to work. On that note, let's think about it... MS Access has had running totals for a very long time. Why did MS not think it important enough to incorporate in SQL Server for over 2 decades? Both are Microsoft products so they can't actually use the "We've never done it that way before" lamety as an excuse. Instead, they use the "By Design" excuse.
Now, if we could just get them to fix PIVOT and a couple dozen other things so they work as well as they do in Access. And what the hell "By Design" process where they thinking of when they "designed" the new splitter function in 2016? And then there are things like the relatively new FORMAT function. I can't believe that they actually did any performance testing there. "By Design", it's comparatively and horribly slow.
Don't get me wrong. I love SQL Server but, "By Design", it's not all that it could be or should be.