I get that for case 2 vs 3, but wouldn't the inner join avoid the null propagation by not attempting to add the null in the first place - if there is no record in table b, then don't attempt to ...

Read this SQL ... In the example above, table1.column1 and table2.column1 are used to combine or join the tables, but only values from table2.column2 are returned. Include more than two tables ...