Post History

In your example, "lot", bunch", "amount", are collective nouns.  There are many collective nouns that aren't quantifiers.  For example: "Microsoft have never said they have extended the free period."  or "The team agreed."

Collective nouns that denote various groupings of animals appear to have started as an upper class hunting fad in England, during the 14th and 15th century.  I am unable to find any earlier examples although I have made some attempts.

Your examples of quantifiers either didn't exist as nouns, or were used with singular verbs exclusively prior to 15th century, which is consistent with the possibility that they got reinterpreted or inspired by the collective nouns originating from hunting jargon (which was no longer mere hunting jargon a few generations down the line).