Agreed.
However, one must look at those doing the writings. There is little Hebrew from the merchants and regular citizens of the era. Virtually none that I am aware of. The only Hebrew that I am aware of is the religious writings of the religious caste of that era.
The Bar Kochba era left behind mundane communications in Hebrew replete with slang and acronyms.
‘Religious caste’ has always had a different meaning for Jews, where ordinary men were always expected to be literate.