OnlyOffice is amazing if you need compatibility with MS Office products. Not saying it’s perfect, and I have and use LibreOffice, but OnlyOffice is better fit than LibreOffice if your goal is to use MSOffice files in FOSS software. I don’t get to decide what files and software my school or work uses, and they use only MSOffice. If I hand my boss or coworker an ODS, they’ll have no clue what to do with it. LibreOffice doesn’t handle XLSX files nearly as cleanly as OnlyOffice.

If I make a table in LibreOffice, even using their open formats, I am giving up some nice features from OpenOffice.

There’s no way OO is just a cheap repackage of LO. They look very different and have different features.