Exclusive Submissions: Sin or Saint?

Is a Demand for Exclusive Submissions to a Publisher Reasonable?
Publishers that are willing to consider un-agented submissions divide themselves into three categories;
1. Those that insist on representations that the submission is exclusive, i.e., that the author is submitting to no other publisher(s) pending a decision from the immediate target publisher
2. Those that openly invite non-exclusive submissions
3. Those that say nothing on the issue
The question is: Is position #1 reasonable? The answer is: Yes. Reviewing a manuscript can take time, sometimes quite a bit, particularly when a long work is submitted. It must be incredibly frustrating for a thorough and thoughtful reader to learn that his or her effort is worthless because the author has already accepted an offer from another publisher.
The question is: Is position #1 reasonable? The answer is: No. Is it reasonable to expect an author to commit to sequential, rather than simultaneous, submissions? Publishers generally take two or more months to render a decision. So an author that has six or more target publishers in mind would have to sign on to a year or more of waiting if they were to respect this group of publishers’ totally rational rules.
So, the subject question #1 has two, equally defensible and opposite answers.
From my admittedly partisan viewpoint as a submitting author, I think the authors have the edge. I base my opinion partially on my occupation as a book reviewer. I can tell after reading twenty or fewer pages of a book whether that book is likely to result in a good review, and a fortiorari, publication. So, frankly, I question whether publishers realistically need to take two or more months to render a verdict on a submitted manuscript. If a publisher’s backlog is so overwhelming that even with cursory reviews it takes multiple months to come to a decision, they should seriously consider closing down submissions until the backlog becomes more manageable.
Of course, many authors, with a fair degree of provocation, will simply lie and say that a particular submission is exclusive. It would be extraordinary if lies of this kind were ever exposed. Nevertheless, there are some authors, including the author of this piece, who will not infect a treasured market with anything less than the unvarnished truth.