if you do not allow simultaneous submissions, you need to pay everyone for the work they can't submit elsewhere. if you can't do that, you should probably take simultaneous submissions and not value the labor of your handful of editors above the work of hundreds of artists

let's say you have a 10 percent acceptance rate. if you send out to 10 journals, 1 will publish you. this is maybe an absurdly high rate, especially if just starting to figure this writing thing out

let's say that a journal usually gets back to you after around 4 months. i'm being generous here, because i have gotten rejections after a year and sometimes no response at all.

you submit your poem one at a time, observing the call not to simultaneously submit. it could take over three years it might take a poem to get accepted. and maybe another 6 months to a year for it to be published. that's a whole college education. a baby is entering kindergarten

there's no true science to this of course. maybe that poem gets picked up immediately. maybe it never does. but who can deny that a poem that gets read by many eyes has a better chance than one held indefinitely in someone's slush pile

the policy privileges the time of the editors (they don't want to read something & discuss it & choose it & then find it's not available) and/or the journal (they want to have the best work/keep others from it). neither thing benefits those who made it or people who read poetry

and if it is a matter of the unpaid labor of editors, it is especially egregious, because they are essentially asking for that cost to be mitigated not just through the unpaid labor of poets (who already seldom make anything) but from (unpublished) poets they will never support

like it's one thing to tie up the work of dean young and then never publish it but it is another to tie up someone who is having to make active financial sacrifices to even attempt to be heard

and to do it because you feel like you can't make those sacrifices yourself. maybe you can't. i am not trying to diminish anyone's work or pretend that editors have easy jobs. but that doesn't justify a very bad policy