Using this SELECT:
select 'some_table' as table_name, jsonb_agg(t.*) as content from some_table t;
If some_table had 1000 rows, are the "column names", which are repeated for each row in "content", sent over the network 1000 times? Or is that somehow optimized away? If the column names are really reapeated once per row, we would spend more bandwith for them, then for the values.