Maybe they didn't explain why for one or more of the following reasons:
- There is no reason why (as it often happens with 'whys' in language)
- There is, but it is too long to explain in a post, as it involves a lengthy explanation of the etymology of "foundation" as well as its historical evolution (for instance).
- There is, but they just don't happen to know.
- They were annoyed by what they considered ungratefulness/rudeness.
- ... (you name it)
- For Teachers