First of all, yes, this sounds very much like the other question with nearly the same title. But it's just nearly the same title.
I understand very well the reasoning about putting a tag into the title, and I'm not here to object this. However, I would like to mention, that using the first (in alphabetical order) tag is really not useful in many situations.
Real time example, which led me to create this question: There is this question on SO that is actually about Python. The user is requesting help in porting a C# script into an equivalent Python script. Therefor he obviously looks for Python help, not C# help. As
C# is alphabetically before
Python though, the website's title makes it look as if it is about C#.
I'm sure there are much better questions in which this becomes much more important. I could think about using some cool technology in some language, and the language being alphabetically before that technology. While the question is actually only about that technology (which is incidentially used in that particular language then), the page title actually lists the language as the important tag - and might hide the question from search results.
It would be good if one could somehow influence the order of the tags, or just specify a main tag somehow, so this could be improved. What do you think?