Completely agree with your analysis, and at the same time cannot fault 1Password for doing this since they are in a position to do it. They are potentially a hundreds of million dollar acquisition if they juice those sub numbers. But they have to do this NOW, because what they are doing is not that difficult, and come the day, as it always does, that Google spies an attractive mechanism to drive more people into their ecosystem and decides they don't want to acquire you, your business will (probably) evaporate overnight.
This, for the vendor, is the other edge of the subscription model. If another flavor of the day arises that costs less, your customer base can swiftly move to this new contestant, especially in the enterprise space, because unlike a fixed license, a subscription isn't a capitalized cost. For Adobe, with their massive ecosystem, this is less practical for their customers, but a password manager? There are already a host of commercial alternatives that to an end user are all more or less the same.