In the end, SQL is what people are familiar with (for better or worse) and what is entrenched in some form in most database, and new versions of the standard are unlikely to change anything fundamental.

I don't believe that adding property graph support to SQL makes much of a difference for SQL and relational databases...

However, the PG query additions (I believe they are close to the Cypher language neo4j) being part of the SQL standard will give a boost to marketing and adoption of PG databases. Vendors can now say "our language follows the SQL standard" instead of referencing cypher and indirectly neo4j. Even if neo4j may have the best intentions, marketing is very important in databases and it is unlikely that vendors could have supported Cypher and thus admit that they are following neo4j rather than leading.

Standards can thus be valuable regardless of whether they are adopted or not and a lot of discussion and collaboration was likely necessary to get to this point re: the PG additions.

In this context, it is also worth mentioning the GQL standard here, which neo4j folks are part of https://en.m.wikipedia.org/wiki/Graph_Query_Language