When the internet was still young, it was common to be force subscribed to a newsletter. As the internet progressed and more websites were created, it became quickly a nuisance to be hammered with several newsletters a week. Since in the beginning most people didn't have a fast internet connection, every useless email was really a big thing. Therefore it didn't take long that it was common for companies to at least offer a possibility to opt-out the option to receive a newsletter. In some countries it was even necessary to offer a 'double opt-in', when a user agreed to receive a newsletter, you had to send a confirmation email and only if they accepted that, you were allowed to send them a newsletter.
Up until this day, I really don't understand why marketing departments still think that a newsletter such a big thing. A newsletter works like those leaflets they throw into your physical mailbox. Most of them are instantly thrown away, maybe 5% of them are being read and eventually up to 1% are having some impact. In the end it really becomes a numbers game, if you have 100 million people force subscribed to a newsletter and 1% react on it, then this can have a good outcome. But most companies don't have this many subscribers, even though I know from experience that start-ups always like to compare themselves to big companies like facebook or twitter.
There are third party services which offer a service for companies to send out bulk emails for them to their customers. The good the thing about this is, they effectively established the rule that companies have to provide an unsubscribe link in their newsletter. Which makes it in most cases easier to unsubscribe from the newsclutter, some webmailers like gmail even offer assistance in this matter. Unfortunately there is a new trend arising because of this, I guess some marketing departments realised that they leaking too many people. Their solution is to force people to login to their profiles first, before allowing them to unsubscribe; "please change your message preferences".
The worst thing is that the majority of newsletters are simply useless. At least some are designed to be either a broad experience for most people in the target audience or carry some useful information about the product itself. Most of them are plain advertisements, annoucing new sales or products, or being just soaked with self praise.
In my opinion the most annoying thing about a forced subscription is depriving people of their choice on which kind of informations they want to receive. Companies should treat their customers which respect and not like herd of mindless consumers. I admit, maybe this is a little bit naive, since most people revert to a mindless state when it comes to acquiring products or services.
But nonetheless, if you don't empower people to be their best self, they never will be.