Let's start with the basics shall we? POWM is meant to be a mean spirited and funny blog. They didn't start the blog to set an example, talk about their favorite tuna packets, give quaint anecdotes about what little Joey said to Santa when he was sitting on his lap. They quite simply started the blog as a bit of fun and others found it funny. They aren't out there pitching to sponsors and sponsors (most sponsors anyway) don't look to them to be role models or act as spokespeople for their products. Quite simply it's meant to be the ultimate in snark. However, even as low brow as their version of comedy is, even they have the decency to mask the identities of their targets, especially minors.
On the other hand, momdot.com actively pitches sponsors, Trisha holds herself up as a model for the mommy blogging community and sponsors want to work with mommy bloggers for not only what societies preconceived notions of what a mom is (mom knows best and mom will never steer you wrong) and should be but because they also know, moms speak to other moms about what works for them.
The problem is, being a mean mommy is pretty much at odds as to what major corporations want in a spokes-mom. That's not to say a mom can't stand up for herself, or fight for what's right, or even lash out after having a bad experience whether it's at the mall or with a bottle of laundry detergent. However, when you delve into picking on children, people who look different than you, or picking on those who look different from what you're used to seeing in your small shitstick town it reeks of at best of jr. high school behavior and at worst intolerance and bigotry. Not really a good example for society at large much less mothers who are tasked with setting an example for their children, and if you have a popular parenting blog, for other moms out there.
On top of that, large corporations are interested in protecting their brands and when they have spokespeople that tarnish their brand then they typically jettison them off.
I do hope that clears up why the lunacy of this comparison is woefully inaccurate.