OnlyOffice is better than LibreOffice for people who want a more direct alternative to Microsoft Office
(it's AGPL... there is an ongoing dispute with a fork now)
(it's AGPL... there is an ongoing dispute with a fork now)
I guess they used "binary blobs" in the broad FOSS-maintainer sense, e.g. bundled third-party assets, fonts, generated/minified JavaScript in sdkjs, and possibly precompiled mobile components...
However, onlyoffice removed their mobile editor repo from Github a few days ago, and EuroOffice has been particularly critical of the mobile apps, claiming they contained proprietary sections. So if there is a concrete concern behind the "binary blobs" accusation, the mobile side seems like the most likely place it was directed at.
It feels a bit like a mudslinging match right now and you were completely right to question the claim :-)