Seriously?
1) You picked out 4 or 5 travel blogs, there are dozens of them (and more) out there. Many focus on only a single topic (Delta, or AA, or a specific region or just on hotels, etc).
2) The few blogs you picked out are all "general" blogs, ie, they dont typically focus on a "single" topic, thus obviously more likely to have similar content to one another, especially when they are all talking about the hot deal of the moment.
3) Each blogger often gives their own viewpoint, which often is in addition to (and sometimes contradicts) viewpoints of other bloggers.
I dont mean to be overly critical of the OP. I can see what he means. But I think he isnt giving enough credit to the hard work of bloggers who try to keep the general masses up to date on the latest and greatest, and also teach people a thing or two.