Freedom of expression exists on a scale. It has two poles, two extremes. On the one end, you're alone in the middle of an empty forest, as far away from everything and everyone as possible. On the other end, you are literally centimeters from someone's ear.
With this image in mind, it's very easy to intuit that you can scream as much and as loud as possible when alone in the desolate forest. It's just as easy to grasp that you might want to tone down your volume as you get closer to the ear. You can common sense your way into an understanding of when it is appropriate to scream and when it isn't.
Just to be absolutely crystal clear: your freedom of expression does not include the right to scream into random people's ears. You are free to express yourself with screams, albeit at a distance.
If you don't take this into account, you get into strange territories when discussing freedom of expression. It does not limit your freedom to use common sense. You can easily understand why you'd not want people to scream in your ear, and with a bit of empathy you can just as easily understand why others wouldn't want it. Yet if you don't, even the most mild-mannered suggestion to please tone it down will be recast as a limitation of your freedom of expression.
Which brings us to the topic of blockbots.
Blockbots are what the name implies: bots for blocking (in this case social media accounts). It's a hassle to block large numbers of accounts, and to boot you have to keep doing it if you want to keep the blocklist updated. It's as easy as apple pie to create new, unblocked accounts, and while it is just as easy to block them as they appear, it gets old after a while.
Why would anyone need a blockbot? The answer is not subtle: because a large number of people are screaming at one's ear, and won't stop no matter how politely one asks them to.
Just as when it comes to sound, volume matters. In this case, it matters in terms of numbers rather than decibel. When a large number of people send what amounts to the same message over and over again, the volume is unbearable. Even more so when responding to any one of them only results in more of the same, and in a sense only serves to pump up the volume.
When a voluminous group of people assemble outside one's residence, it is only prudent to close doors and windows in order to keep the noise out. The same goes for social media: volume speaks louder than words.
Blockbots are, to put it bluntly, volume control.