Actually I was using the Print Spooler as an example, and it predates DOS
    by a wide margin. IBM mainframes used a similar task as did digitals minis
    and so on. In fact linux actually creates a "spooler" directory for each
    users account.

I think you'll find that the original use of "spooling" was to send
printer or cardpunch output to a magtape rather than a physical printer.
Magtape speeds were more matched with CPU speeds, and this avoided having
the ($$$$$$$$) CPU have to sit around and wait for the (slow) printer.
An appropriately equipped printer could print directly from the magtape.
IIRC, "SPOOL" is an acronym, and one of the "O"s is for "offline."

Whether there is a print spooling application on your computer is
completely separate from whether the printer hardware uses interrupts or
not.  Printer interrupts are neither necessary nor sufficient to
implement spooling (in the modern sense of "spooling."

I suspect the original intent was for PC printers to use the interrupt
line, but that there was such variation in the printer-side
implementation of the signal that this proved to be impractical.  You
really do NOT want "interrupt per character" behavior on a high speed
printer (interestingly, some serial UARTS have similar problems -
dispite FIFOs, they end up doing per-character interupts.)  OTHO, some
of the "printer buffers" that go in between your computer and the
printer COULD more easily make good use of interrupts - I don't know
whether any of them do.

BillW