It works ok without it:

    ---- 8< ---- z.sh
    #!/bin/bash -e

    {
        read A
        read B
    } < <(echo -e 'AAA\nBBB')

    echo $A
    echo $B
    ---- 8< ----

    $ ./z.sh
    AAA
    BBB
    $ echo $?
    0

/cc @kazuhiko