This one talks more about the two year process. https://www.washingtonpost.com/life...l5HOxS6n3AwIT_6N1XBXyg&utm_term=.96b221fc62a4I haven't commented because I mostly agree with you, but I can put my thoughts into writing.
The article wittily points out that 95% of the book consists of interview transcripts, so there's hardly any material that would've taken 2 years to write.
But as far as Howard's maturity, he certainly takes a different tone with celebrities now. But he still has major problems. Look at what he did to Lorde. She (like many people) boycotted Israel because of the civil war going on there, and while Howard has the right to disagree with that decision, he completely loses it on her, in a Trump-level juvenile tirade. Her music's shitty, she had one hit but it sucked - it was nonsensical and should not have been popular, she's got no talent, she's ugly and stupid, she'll never have any success ever again.
He does the same thing with any caller who he disagrees with. Howard either filibusters (which is particularly easy for him to do) or cuts-off the caller.
According to Howard, JD's life is odd; Memet's life is odd; Gary's life is odd. Yet Howard has the oddest life. He gets take-out from the same chinese place every day for decades, yet he doesn't know the name of anything on the menu. He can't use a public bathroom. He eats the same food every day. He doesn't understand the idea of eating food while watching a game on TV. He doesn't know what a vagina looks like. He turns hobbies into obsessions - chess, photography, painting; but everyone else's interests are stupid. Every season, he comes to the realization that The Bachelor doesn't reflect real life, but then he keeps tuning in.
He and Beth are waging a futile battle with rescuing animals. It's like he's trying to adopt all the dogs and cats himself. It doesn't work: there will always be more. He can't just do his part, he obsesses.