Can someone dig the reasons behind emphasis regexp limitations?

[Ihor Radchenko]

Org allows *emphasis* markers to be surrounded by spaces to some markup:
1. Before opening emphasis marker we can have
   space; -('"{
2. After closing emphasis marker we can have
   space; -.,;:!?'")}\[

(see org-element--parse-generic-emphasis)

I keep looking at these rules and remain confused, even though I do
remember that Nicolas stated good reasons for this.

But... Why "[" can be after closing marker and _not_ before opening
marker. It is counter-intuitive. And what about "]"?

Can somebody dig into that mailing list archives and figure out the
reasons why some characters are allowed and some now. I will then put
them into code comments or maybe even into Org syntax spec.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
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