Very few people have suggested that MN intellectual property has been looted. And I do agree that it hasn't been, significantly (but there is the buggy thread with the toss-OP-into-crowded-forum-and-retire posting approach).
IMO Janice Turner is under attack largely because she wrote a lazy and unbalanced "all modern parents are shit, not like I was" article while still fuming from the incident involving her parents. The fact she's a Mumsnetter is seen as making that worse, admittedly, but I think because as a Mumsnetter she should know that it's just not true.
It's not a hanging offence, just a bit crap and unprofessional, just as it is crap and unprofessional when if I let stuff that happens at home affect my work performance too much.
It's been widely known for years that JT is a Mumsnetter -- she mentions it herself. When she writes articles that the majority here agree with she gets kudos on MN, with generally a little extra kudos for the frisson of knowing that it was written by One Of Us. Now she writes an article that is less popular and she gets brickbats, a few hurled with extra heft because she is One Of Us.
JT has written articles in which she's commented on bf in church herself 2003: "I've had my nips out for the lads in church" so I'm not sure why she's down on it now, unless it's a self-abasing "I, too, am a tosser" thing.
We are parents -- how do we suggest all parents are tossers? We suggest that parents who do X, Y and Z are tossers, frequently and with great enthusiasm, but tend not to make such sweeping generalisations. Or if we do, then we get jumped on in much the way that TDW/JT has been.