But generating a table with all numbers was just a throwaway example of the LATERAL JOIN syntax/use, and (hopefully) not what you'd actually use it for in the real world.
It's not clear to me that (mathematically) a lateral join can be reduced to a recursive cte (and if the performance of a recursive cte would be acceptable for the cases where it does work as a substitute).
WITH RECURSIVE cnt(x) AS ( SELECT 1 UNION ALL SELECT x+1 FROM cnt LIMIT 5 ) SELECT x FROM cnt;
And then do a regular CROSS JOIN on that table.