The Lebanese have been saying “bét” for at least 3200 years, now they say “bét” but it suddenly from a “dialect” of Arabic. It is foolish to think that a population will speak a language, say Aramaized Canaanite, plus local variations, then suddenly, tabula rasa, switch to another one for the samewords.
It would be an anachronism to assert that Italian is a dialect of Catalan, but safe to say that Italian comes from (vulgar) Latin. But when it comes to Lebanese (more generally NorthWestern Levantine), the “politically correct” Arabist-think-tank view (low-IQ Westerners trained into something called “Middle East Studies”) is that is is derived from Arabic (Lebanese “dialect” of Arabic) to accommodate sensitivities — even linguists find circular arguments to violate the arrow of time to serve the interest of panArabism. In situations where there are similarities between a word used in Leb and Arabic, they insist it is derived from Arabic not from a common root of both. (Most Lebanese are confused by diglossia as one is not supposed to write in the spoken language). Unlike Indo-European languages, Semitic languages have a criss-cross of roots and considerable areal diffusion to assert clean descendance, hence statements such as “A is a dialect of B” don’t have the certainty and neatness found elsewhere, which we will argue, requires orthogonal factors. Even Arabic is ill defined (historically, it may be referencing a nonpeninsular Western population) and the definition “Arabic” is largely circular. To make things more complicated, linguists call “Arabic” isn’t classical Arabic but some hypothetical construction called “Proto-Arabic” — so linguists and politicians don’t even mean the same thing.