Accidentally all software you cite are born as commercial product: LibreOffice's origins are StartOffice, originally developed by StarWriter and after acquired by SUN; it became a FOSS project when SUN understand it can't profit anymore from it due to Microsoft Office popularity. Firefox was born as a commercial product (Netscape, originally an AOL product) that mimic Mosaic, but does not use it's free code. Blender was born as an internal product of NeoGeo, after distributed as a shareware by another company NaN and only after nan bankruptcy as a FOSS product. Eclipse born as a commercial IBM IDE, successors of VisualAge Micro Edition...

Of course, there are "recent" FOSS project with a design that take inspiration from commercial products, simply because that's the way authors think/know even if the code is free, but original FOSS software are another story.

maybe for LO and FF, but I don't think that you can present yourself as a proficient blender or eclipse user if you don't write your own plug-ins