From what I've seen, dropping an entire series on the same date has mostly been a Netflix phenomenon. They release so much content that they can probably do so without hurting their bottom line. Amazon may have done the same in the past. Most other services release so few original series that they need to retain subscribers and stretch subscriptions as long as possible. People could wait until the final episode airs and then binge, of course, but that may not happen with highly anticipated titles.
I only subscribe to streaming services a month or two at a time then cancel when I run out of new titles. Amazon video typically only gets activated around Prime Day and Black Friday when there are other benefits to subscribing.