That last paragraph is one of the most incisive comments I've read on HN.
I'll just add that there's a feedback loop. The more parents infantile their children, the longer the children tend to take to grow up, and the more the parents will feel like the children are infants.
I'll second this notion. I know of a grown family (youngest in early 40's) and without exception, they're all adult-children, incapable of forging ahead in this world. Their parents have continually bailed them out of bad decisions, bad marriages, bad businesses for 2 decades. The only problem is now the parents made some bad business decisions so the whole family unit is in big trouble. I've seen a grown man in his 40's crying to his Mum, who comforts him with the sorts of noises you would to soothe a 5 year old. I'm not talking about 'my friend died' here - I'm talking about 'my life sucks and I hate my job'
I'll just add that there's a feedback loop. The more parents infantile their children, the longer the children tend to take to grow up, and the more the parents will feel like the children are infants.