Omid Scobie, co-author of bestseller Finding Freedom, says the couple have been "thriving" since the split and the new streaming deal shows they're finally "operating" how they've always wanted.
"This is the couple operating in a way they were desperate to for some time but couldn't for a number of reasons, many of which tie into what is considered too politically sensitive or not," he said in a recent episode of his podcast Heirpod.
Harry and Meghan are "absolutely happy" now that they've "taken their careers as philanthropists to a whole other level", Mr Scobie claimed.
"It shows how much they were held back by tradition, hierarchy and stubbornness within the institution."
While speaking on the popular podcast, the royal biographer was asked: "If The Firm is so experienced of working with powerful world leaders, why couldn't they handle working with Meghan?"
He replied: "There is no more pragmatic a family than the royal family and I think they are capable of having positive and healthy relationships with anyone.
"As we've seen, this wasn't necessarily about the relationships between the royal family members and Meghan, it was about the institution of monarchy and how they supported Meghan.
"Had Meghan of come in and done everything by the book, rather than ever come up with her own ideas, or challenge a way of working, or bring in her own ideals than it may have been very different. But that is not what we can realistically expect from a human being."
Meghan's strong personality and opinions simply didn't work within the confines of royal tradition, according to Mr Scobie.
"Harry loved her dynamism, it's what made her so exciting to be a team mate with," he said.
"It was that, and the things that we often celebrate about Meghan internally just didn't fit in with the way things were done in the institution.
"Rather than anyone trying to accommodate those differences, it was quickly seen as something very problematic and something many tried to extinguish through leaking stories to the press and making the couple's lives difficult internally."
He added: "It's why now we see them thrive now in a way we haven't seen in a long time. I mean how much have they achieved in a short period of time since leaving the Royal Family?
"You only need to look at the work they are doing and how vocal they've been about things that are so important to them."
Mr Scobie knows Harry and Meghan well after years as a member of the royal press pack.
The couple have strongly denied speaking with him for Finding Freedom, insisting they had nothing to do with the book.
However there's been speculation that they had some contact with Mr Scobie and fellow author Carolyn Durant due to the number of very personal anecdotes in the biography.