Why would wine sellers need to broach the cask? I don't know if wine merchants still broach the cask in 2021, but why would they? Aren't casks manufactured with a spigot that a seller can just turn on, as shown below? I embolded the phrase below.

broker [14]


Broker has no connection with the
past tense of break. It comes from Anglo-
Norman brocour ‘small trader’, but its ultimate
origin is not clear. A variant Anglo-Norman
form abrocour has fuelled speculation as to a
link with Spanish alboroque ‘sealing of a
bargain’ and Portuguese alborcar ‘barter’,
which are presumably of Arabic origin (the al- representing
the Arabic definite article); but
other etymologists have sought to link the word
with broach, as if the underlying sense were
‘someone who sells wine from [that is, by
broaching] the cask’, and hence any ‘retailer’.

Word Origins (2005 2e) by John Ayto. p 77 Left column.
I believe that during aging, spigots aren’t inserted into the casks. I’m guessing that plugs are more reliable, allow tighter storage and are cheaper.