It has been a while so maybe things have changed, but the main reasons I remember are 1) lists stored as a property must be a homogeneous list of simple builtin datatypes so no mixing of types, custom types, or language tagging like RDF has as first class concepts. 2) indexes on lists are much more limited ( exact match only iirc) so depending on the size of the data and the search parameters it could be a big performance issue. 3) cypher gets cumbersome if you have many multi-valued properties because every clause becomes any(elem in node.foo where <clause>). In Sparql it's just ?node schema:foo <clause>.

I don't think everybody should run away from property graphs for RDF or anything, in terms of the whole package they are probably the right technical call ninety-something percent of the time. I just find Neo4J's fairly consistent mischaracterization annoying and I have a soft spot for how amazingly flexible RDF is, especially with RDF-star.