"So, do blogs like this give us a more accurate impression of the tenure-track life or do they amplify the negative, leading some people to conclude that pre-tenure suffering is de rigueur?"
This question can be asked about any aspect of life.
Whether it is tenure-track in a US university or teaching in a college or being a student in India, a working mother or a retired person, many people use their blogs to vent their daily disappointments, post their rants and criticisms. Some blogs are downright obnoxious.
Of course there are exceptions --- and ---
How many of us blog about "I am happy today!" ?
"I finished all my corrections and returned all my students' records Yay!"-- (I just did that today)
So blogs are disproportionately pessimistic.
If one were to obtain ones world-view from blogs, one would be depressed totally.