They've initialized this crackdown in a few different waves. I can't imagine they would continue to do it if it were detrimental to their bottom line.
Companies regularly do things that are detrimental to their bottom line because they either misunderstood how their customers use their product, or because they are trying to please shareholders, or a combination of both.
The question begging to be asked here is whether those are new subscribers or people that were using someone's else password, natural growth, or just a good show landed in meantime and a bunch of people subscribed
It's an increasingly crowded market, everyone's distracted, everyone's sick of subscriptions, and nobody has enough money. If I was going to alienate a major chunk of my userbase, this would not have been the time I would've picked.
It does seem like this was a plan that was in the works for a couple years, and momentum is keeping it moving. I doubt they would have picked this timing if they knew what was coming!
But in reality they end up losing the 1 account instead because none of the 3 people are willing to pay full price individually. They were all willing to pay 1/3 of the price when sharing.