Arfarfa, you really need to have tried it before you can spout. I, for example, got married on exactly the basis you describe - for life - and had children, intending that they should be as secure as two loving parents can make them. My husband had Issues which got worse over the years and impacted very badly on my own mental health. There were a few indicators early on that I didn't pick up on, sure, and a few which of course I thought I could help him with, as you do. I just didn't think leaving was an option. I thought staying and working it out was the right thing to do, and for a while sometimes I thought it was working, then it was back to the madness, in a constant cycle for a quarter century.
It took 25 years to get smart and get out. I just so totally wish I had done it years earlier. I don't know about him, but the rest of us would have been better off financially without his hopeless idea of business and his addiction to buying needless junk. Yes I am on benefits now, but not because I'm a single parent; it's because I lost my job due to the depression caused by living with a loony. Had I left him years ago, likely I would still be employed and not troubling the benefits system, as well as being a bit happier in my own skin. He, on the other hand, would have either found some other woman to sponge off, or actually engaged with Planet Earth before he got too old and mad to make a go of it.
Tired of him? Reneging on my commitment? He never knocked me about, as far as I know he never cheated, he always brought me a cup of tea in the morning and encouraged me to put my feet up when I got home in the evening. Sometimes we had a laugh together and we had a reasonably active sex life for around 23 years. So were things "extreme" enough to merit leaving? Hell yeah. You needed to live in that house, you needed to be a fly on the wall in our bedroom, you needed to see inside my poor head to know just why that marriage was A Bad Thing.
Oh, and youngest DC is still getting over the emotional problems caused by living with his biological father, as that stupid article puts it. The school had to involve social services to ensure DC lived with me only, because they were so concerned about the effect on the poor mite. Again, his father never physically abused nor starved him, but showed him affection and made sure he got to school on time. Extreme enough? The professionals certainly thought so, and we all breathed a sigh of relief when I brought my precious boy home for good. He does still see his father, but in small doses that shouldn't do too much harm.
Do not presume to pronounce on what other people should be doing until you have walked a mile in their shoes.
Btw, as a side issue, having children is neither a right nor a privilege. It is a biological function. For some, I would go so far as to say, it is a biological imperative. A stable, monogamous relationship is a good way to bring up children but it isn't the only way (thank God).