Except Sveriges Riksbank is the central bank of Sweden. It doesn't care much about name recognition, and given the name and design of the prize clearly desired a strong association of its prize with the Nobels.

If there's any slight it's to Alfred Nobel, who didn't create a prize for economics.[1] Apparently Nobel's great-great-nephew was upset by the conflation. "In 2001 [he] asked the Bank of Sweden to differentiate its award to economists given 'in Alfred Nobel's memory' from the five other awards". See https://en.wikipedia.org/wiki/Alfred_Nobel#cite_note-31

[1] Is there any evidence that this was deliberate? If not then I fail to see what's substantively lost in the conflation.