Characters 9-11 are NOT AT ALL "Optional" as they name precisely the branch the receiving account, the numbers that must be included AFTER the SWIFT branch code for the wire to actually "Go Out".
Your "Source" is the PR face of an electronic payments system that started in 2019. They have a very selective view on "informing" the average UK reader on remittances, as they're trying to steer readers to their partners, so as to legally skim the FX spread, plus Agio.
Wire services date to the introduction of the telegraph, with Trusted source, such as the Fed Wire System being key, but are sourced in private bank "Letters of Credit". The bazaar banking system is even older than that.
moneytransfers.com is a nice slide site owned by intent.uk
It's an advertisement, notsauce.