Hopefully I can provide insight into why your questions were closed (and, in any case, meta is the best place to discuss - thank you for bringing this discussion to meta).
Will only generate discussion if the person answering unsure own answer.
Your question stated "Why are they doing this[?]" which invites speculation. This wording is likely why it was closed as "not constructive".
Absolute URLs omitting the protocol (scheme) in order to preserve the one of the current page is approximately the same question - asked in a different way - and answered at StackOverflow over a year ago.
I do not understand why my question was closed?
This question was closed as "off topic" because it is not covered by the topics listed in our FAQ:
If your question generally covers the operation of websites which you
control, then you’re in the right place to ask your question!
or CSS coding, it might be a better fit on Stack Overflow. We prefer
questions here about problems or issues that affect entire websites.