I know of at least one commercial DBMS that will perform this transformation automatically in some circumstances, and I’d be surprised if most of the other major systems couldn’t do the same.
The problem is the more optimizations you implement the more possibilities the query planner has to evalue which may result in (1) a too long query planning phase or (2) the possibility of de-optimizing a good query because an optimization was falsely predicted to be faster
Additionally, in this example, the rewritten query is easier to read and maintain.