The short answer is: because these are newgroups, and that's the way
they work.

Newsservers usually have a fixed amount of storage space for each
newsgroup, and drop off older posts as new ones come in. This allows the
thousands of linked newsservers to maintain a modest number of relevant
conversations without the terabytes of storage that Google Groups
maintains.

In article ,
"Hari" wrote:

Might not be the correct forum... but,

Why is it that if you try to access old questions from the Microsoft web
page (excel newsgroups) it is not available.

I know that I can use google but why is it that if Google can archive/keep
Microsoft's stuff, MS itself is not doing that