Workforce reduction due to Hubs has weird calculation

[RustyGrandChevy]

10% reduced workforce reduction due to Stockpile Hubs does not apply to additional buildings which are build on a district.

Not sure if that is how it should be.
If I am about to place a, let`s say a Fuel Stockpile Hub, the tooltip says it

"reduces the need for labour in neighbouring extraction districts"

As the buildings, such as dust coal mine are placed on that district I would assume that worforce reduction applies to the coal mine as well, but it does not.
Makes no sense to me. It feels that it makes the Stockpile Hub almost useless as it demands 100 worforce by itself.

[adrien_perleflamme]

Just have two districts nearby any such hub and you have a net positive of workforce. Besides, stockpile hubs have another, actually main, feature: they provide a bigger stockpile.

[CreativityBrain]

+1