The second article is about the ability of the DSCOVR satellite to capture full-disc images of the Earth (no mosaicing). "Other images of Earth were created using digital stitching techniques, but for 43 years, until DSCOVR’s launch, it was also the only full-disc image of the Earth in existence."
That seems like it could be true, in the absence of counterexamples.
Looks pretty full disk to me.
https://en.wikipedia.org/wiki/Geostationary_Operational_Envi...
The list of MEO to GEO satellites with imaging sesnsors capable of doing this is probaly longer than just GEOS and METEOSAT.
https://earth.esa.int/web/eoportal/satellite-missions/m/mete...
also these: https://www.metabunk.org/full-disk-hd-images-of-the-earth-fr...
It used to be these images, more than the Earthrise one, which were considered instrumental in the rise of a new global awareness.
https://earthobservatory.nasa.gov/images/36019/earth-viewed-...
https://www.lpi.usra.edu/resources/apollo/catalog/70mm/missi...
Anyway, this text is clear: "Alternately known as Triana, Goresat, or by its current name, DSCOVR (Deep Space Climate Observatory), it’s the first earth science mission distant enough from our planet to capture its entire sunlit surface in a single photograph (only one such photograph, shot from Apollo 17, was previously in existence). And it does so multiple times a day, every day—with the results posted online by NASA, ready for public consumption within 12 to 36 hours."
We can get pedantic about this, but the message of the second article is that the occasion when the Blue Marble was taken was a rare opportunity, with the consequence that there wasn't really a choice or supply of up-to-date full-disc images until DSCOVR.
(https://www.artsy.net/article/artsy-editorial-one-photograph...)
None of us here actually knows everything about these complex space exploration missions, let alone participated in them. It looks pretty silly and pretentious to try playing "know it all" about an endeavour that is way above our pay grade.