Simultaneous Submissions

I am now mostly submitting to magazines that do not accept simultaneous submissions.  Why? Not why am I submitting to these magazines (they are generally higher echelon magazines,) but why don't they accept simultaneous submissions?  I mean, really.  What's the big deal?  It is okay for writers to experience constant rejection, but not magazines?  In other words, are these magazine's egos so precious that if they accept a poem, and then learn that the writer had neglected to tell them that the same poem had been accepted somewhere else a month earlier, it is an affront that can't be countenanced?  I actually accidentally submitted simultaneously to a magazine that does not take simultaneous submissions and the magazine sent me a scathing letter barring me for life from submitting to it (because of an honest mistake).  Really?  I still laugh about that to myself once in a while.  Perhaps magazines do it to simply limit the number of submissions they receive.  Really?  Does it work?  It seems self-defeating: why would you want to limit the number of submissions you receive?  Having edited two magazines myself, it seems quite easy to eliminate (for whatever arbitrary editorial reason you espouse) about 95% of the submissions one receives on a quick read; sometimes just the first line tells you everything you need to know (sorry, the very human mind at work).  But, if, for whatever reason, (and I suspect the only real reason is because the big magazines can do it,) a magazine does not take simultaneous submissions, I think a necessary concurrent policy is that the turn around time should not exceed four weeks, six weeks at the most.  Otherwise, you put writers in the extremely difficult position of not getting poems published until years after a poem is written, if at all.  If "magazine a" takes six months to a year to respond to a submission, and then so do "magazine b" and "magazine c", etc., by the time "magazine g" sees the poem, the poet will have evolved, the world of poetry will have evolved, and a very good poem may have become stale, either in the eyes of the poet or the world.  Any policy other than accepting simultaneous submissions or not accepting them but promising a very rapid turnaround is only inconsiderate and insecure.  It is certainly not writer friendly.