Proposal: Hebrew Language
Proposal: Arabic language (اللغة العربية)
Both of these proposals have been proposed before but were closed, and are now only in the definition phase. Moreover, it's a pity that some languages like Aramaic, Ugaritic and Akkadian will never reach the required number of followers to justify a separate site.
The concepts in other semitic languages are relevant to both Arabic and Hebrew, especially from an etymological point of view. There are several study programmes in classical Hebrew worldwide that include courses about Aramaic and other semitic languages to provide students with more context. (I don't know how this is for Arabic.) On research-level there are very interesting publications that use both Hebrew and Arabic data, focusing on phonology, word order, the role and restoration of vowels, aspect, etc.
Sure, for people who come for the modern Hebrew and Arabic, these arguments will be less convincing. But compare to other sites. On Philosophy.SE, some specialise in eastern philosophy, others in classical, others in twentieth-century philosophy. There are always questions on a site that are not of interest to you. But incidentally there are questions about the relationship between different fields, some of which you are familiar with. By separating the sites, these questions don't have a real place. Had Stack Overflow been separated by programming language, there had been no real place for questions about generating dynamic HTML pages using PHP.
For questions written in Arabic, Hebrew, or other languages other than English, I see two solutions. Either don't allow them, or make sure that there is at least one moderator of every spoken language (which will probably only be needed for Hebrew and Arabic).
I believe that using tags for 'arabic', 'hebrew', 'aramaic', 'biblical-hebrew', 'ugaritic', etc., it is possible for users with any specialisation to use the site comfortably, by ignoring / favouring tags. And, if we would merge these two proposals and include other semitic languages, we give questions on linguistics a proper home.
What would you think about creating a new "Semitic languages" proposals by merging the Hebrew and Arabic proposals?