KOffice started in October, 2000.
OpenOffice.org had the first release only in 2002.
So, in your logic, the LibreOffice developers should join to AbiWord or KOffice (now Calligra), because the wheel already existed when LibreOffice was started. They were reinventing the wheel, and the worst, using Java.
Hey, this is FOSS. Each application has its merits.