As I reel from yet another journal rejection, I take solace in the fact that: (a.) my batting average is still above .300 (is that good, bad, normal? I don't know!), and (b.) my "lucky journal," BBR, is about to publish an article of mine on John 21. Yet even so, for every acceptance e-mail by a journal editor, I still see two rejections, and rejections are not pleasant! (For me, the temptation after a rejection is to drive to Pick'N'Save, purchase a "family-size" bag of potato chips, and not share it with my family, if you get my drift).
Never fear, dear reader, this post is not meant to be a "pity-party," but rather to answer the question, why go through peer-review (for both journals and books) when it's much easier to self-publish?
The peer-review process is not perfect, of course (click here for a helpful Scholastica post on the topic), nor do I wish to suggest that "peer review" is a monolithic entity, equally applicable or beneficial in all circumstances. Furthermore, there are occasionally legitimate reasons for self-publishing, or publishing "in-house" by a small organization (I'm thinking especially of missions or niche works that would only be of interest to a small group of people).
Nonetheless, I can stress three good reasons why peer-review is important for theology and biblical studies. First, Proverbs 27:2--"Let another man praise thee, and not thine own mouth; a stranger, and not thine own lips." In other words, affirmation of the worth/value of something I have accomplished should come from others. When I self-publish, generally speaking, I am affirming my own work. I expect others to purchase my book only because I wrote it (and probably convinced a few good friends to say nice things about it on social media, people who would say nice things about anything I wrote!). In contrast, when I publish through an organization that has to make choices about what they publish, the fact that it gets published at all is a testament to its potential value. This is even more so when my article or book is vetted through a blind-peer review process, where an established scholar(s), without knowing who I am, determines whether my paper is worth publishing or not.
Secondly, accountability. If I self-publish, I can make any claims I want to, utilize twisted logic, and still expect a whole bunch of people to believe what I say. Case in point: when I was in college, an popular e-mail was being circulated, sent out to distribution lists, about how "NASA scientists, using a supercomputer, have discovered Joshua's missing day!" It was, of course, pure malarkey, and could not be traced to a reputable source. [For the record, I believe that whatever happened in Joshua 10 was a miracle; but I highly doubt that it's the sort of miracle that could be "proved" with a supercomputer 3,000+ years after the fact!] Despite this, the story continued to circulate as a "legitimate" piece of Christian apologetics. The point is, the peer-review process is meant to weed out untested postulations or, worse, tall tails (i.e., "lies"). If somebody is careless, they don't get published, at least in theory.
Thirdly, respectability. Precisely because an article in Tyndale Bulletin has gone through a rigorous peer-review process, it is more likely be worthy of my attention. Precisely because a book published by Eerdmans had to have convinced an experienced and intelligent editor of its value (an editor who quite possibly has a PhD herself), that book is more likely to be worthy of my attention. Exceptions exist, of course. If somebody I personally know and respect writes a book and self-publishes it, I'll probably respect that person's book as well (and perhaps even endorse it for them). But I would not expect it to make any ground-breaking contributions to my understanding of Scripture.
Now, all this does not mean that garbage never gets published via peer-review, or that reviewer bias never impacts acceptance or rejection of an article or book (after all, wouldn't a reviewer naturally gravitate towards those articles that prove something he or she already believes?) Nonetheless, the peer-review process is helpful for those reasons listed above. Those who truly wish to contribute to theology at a higher level than "99-cent Kindle specials" or "personal blog" (like this one!) should keep that in mind.