A while ago this year I answered the following question:
Valid question, accepted answer with some upvotes (we don't get massive numbers on expats.SE) - and the answer is simply a table. In fact, there cannot be a valid answer to such a question which is table-less. (Ok, you could "spell out" the contents of a table as plain text, but that's still a table in disguise).
I believe this example illustrates why it is inconsistent for Stack Exchange not to offer table rendering in answers.
What are the reasons that such support has not yet been made available? Even if there had been some technical issues at the outset - after nearly a decade since Stack Overflow got started, surely that's not what's holding this feature back...?
... But note that I've not asked about markdown specifically - whatever arrangement for rendering tables is better than none. Also note this is not a feature request, it's a request for information regarding why this feature has not been introduced despite requests by others.