It's not that the author is affiliated with facebook.
The point is that for most startups, you validate your ideas from your kitchen table, fighting to get a handful of visitors to visit your site.
When facebook launches a product at blasts an infinite firehose of users at the product.
So the facebook experience is utterly different to the startup experience and really its kind of absurd to be sitting in facebook advising startups how to do what they do at facebook, they're such disconnected experiences.
Maybe the topic of the article should have been "how to validate a new product coming out of one of the biggest tech companies that ever existed, advice for other product managers from FAANG".
I just can't believe you're talking about Facebook like it's some restaurant franchise.
Never mind that your math doesn't even make sense. Even if only 1% of users retain after a year, 1% of 100m is 1m more than your 90% retention of 0 users.
Being inside FB (or any other large company) has way more advantages than users entering the door.
Just the metrics and analytics that FB can gather on experiments is an insanely huge hill a regular startup can't climb. FB can gather and analise data at a scale, on so many markets and devices and demographics that none other plan tier at 3rd party integrations can hope to match. The SRE support you get, a 30 minute conversation with other great product managers, engineers, designers one meeting invite away, a history of what others have tried and what worked and what didn't, and so much more.
And if you get a VP to support you, even for a bit, we're basically talking about a torrent of money and resources being thrown at your project while you still drawn a 6 figure salary (plus benefits and bonus and stocks!). It's really apples to oranges here.