Absolutely not true in my experience. MySQL has its share of issues (all DBs do) but it is rock-solid when using the correct engine (InnoDB for most cases, RocksDB for high-throughput writes, Memory for caching). MySQL is very hard to beat for very high-volume OLTP workloads, both reads and writes. Its replication systems were years ahead of other systems (SQL Server, Postgres, SQLite doesn't have replication). DuckDB AFAIK is OLAP and they don't compete in the same space. Every DB system has "the things its good at" and MySQL really shines at very high-volume OLTP spread across partitions.
Today it just seems odd that anybody is still using MySQL. Postgres? Sure. SQLlite? Hell yeah! DuckDB? Of course. MySQL? Not so much.