One of MERGEs goals is to be the ANSI standard for "Upsert" queries, yes, ("On Conflict Do Update" is not standardized) but it's also a more powerful tool than

One of MERGEs goals is to be the ANSI standard for "Upsert" queries, yes, ("On Conflict Do Update" is not standardized) but it's also a more powerful tool than that. It's almost a full bulk ETL tool allowing for some complex multi-table join-based bulk INSERT/UPDATE/DELETE (all at once). (With great power comes great responsibility; as others point out MERGE in SQL Server can get you big table deadlocks if you aren't careful, but on the flipside in my experience there were a lot of very hairy stored procedures I was able to rewrite as single much easier to read MERGE statements that had far better query plans and were much faster overall.)