The more recent edits to the .net tag for instance, has a lot of information copy, presumably from questions that were closed. I don't think this is a good idea.
First of all Stack Overflow isn't Wikipedia. And I don't think Stack Overflow tries to compete with Wikipedia on the same turf. But right now it looks like a badly maintained Wikipedia page.
What's the purpose of a tag wiki? Isn't a tag wiki just supposed to explain the tag?
If you read the revisions from bottom to top, it's like watching a reasonable man slowly go insane with information overload.
There is also meta-discussion, which I don't think belongs there:
As such, questions like "How do I do file I/O in C#?" should really be "How do I do file I/O with .NET?". Because such a question concerns the file I/O libraries provided by the .NET Framework, it should be tagged with both the .net tag, and with the c# tag, to indicate that you'd like the answer to be written in the C# programming language.
That section sounds like a moderator talking to himself. I don't think average site users will read that and go "Oh! OK. I'll make sure to do that."
I personally liked the original edit:
Questions relating to Microsoft's .net framework.