Why doesn't Space.SE use icons yet?
A simple explanation is because the site is still in Beta. All Beta SE sites (except the sponsored one, like QuantumComputing.SE and ArtificialIntelligence.SE) will have the generic beta theme, including favicon with an SE-bubble with either letter or symbol inside it.
The more complex detail is... since Design-...
Because answer acceptance only indicates that it helps the asker the most, while the vote indicates the community's voice.
From the help center,
Accepting an answer is not meant to be a definitive and final statement indicating that the question has now been answered perfectly. It simply means that the author received an answer that worked for them ...
@AndrewT.s answer sums it up nicely. Here's some additional background:
The Stack Exchange ecosystem is an offshoot of Stack Overflow where in the beginning questions were almost always problems. They still are today pretty much as well. Then and there, acceptance was almost synonymous with "That solved my problem".
While SE is a little different, and ...
Stack Exchange Data Explorer might at least help; you can search posts by the deleted owner's display name.
Posts by deleted owner's display name
SELECT Id AS [Post Link], Score, Body
WHERE PostTypeId <=2 AND OwnerUserId IS NULL AND OwnerDisplayName = '##DisplayName##'
ORDER BY CreationDate ASC
(not tested thoroughly, might be buggy)