The simplest argument is that if your job requires you to share documents with other people who are used to using Office document formats as their standard exchange medium, then unless you convince those people to move away from that format -- which may require either moving everyone
else they exchange documents away from that format, or treating you as a special snowflake -- you're stuck.
If you're in a tech space full of plain text document formats, dealing with folks who love Markdown and use programmer-centric diff tools, all of this can certainly be irrelevant. (I'm in that space in my day job and with personal projects that don't involve other people.) But for a lot of, well, office jobs, that's a non-starter. And Google Docs, while it has some great things to recommend it, doesn't have the feature set Office does. (There's a long-standing observation that while most users only use 20% of Microsoft Word's features, for any two given users that 20% may not be identical.)
I work with fiction editors, and I need to be able round-trip manuscripts with embedded comments and revision tracking. Google Docs doesn't cut it for me. Actually, none of the OO-based suites (LO, AOO or NeoOffice) were able to round-trip transparently with Microsoft Word in my admittedly limited testing back in 2014, although that may no longer be the case. (They all have the required functionality, but bits and bobs of formatting and metadata would go away when the document moved from LO to Word back to LO.)
tl;dr: LibreOffice will matter as long as Microsoft Office matters, and whether we like it or not, in an awful lot of the business world, Microsoft Office still matters a whole lot.