Fourth reason: Twitters product, while useful to news junkies and journalists who report on it, is actually inferior to the average person who simply wants to interact with their friends, aka Facebook.
They don't use Facebook because its algorithmic "timeline" isn't realtime in any sense of the word and they consider themselves more than capable enough to decide on their own what's worth their time or not, they don't want to be fed things / advertisments somebody else wants them to see.
They'll probably all switch to the next best thing available once Twitter's rumoured algorithmic timeline is to be introduced.
Personally, I left the whole Twittersphere way back when the alienated their third party devs, for me that was more than enough indication of the way they were heading. Nowadays they have nobody left who could actually come up with the Next Big Thing (tm) for Twitter, because all of their engineers are mostlikely busy trying to figure out how to commercialize the platform in the shortest amount of time in order to satisfy their shareholders.
Good that they use AdBlock then, cause Twitter puts ads in your feed.
In the future they might see whatever Twitter thinks is important to them, which might still be ads, but in the form of other peoples / companies tweets which just "happen" to end up in their "timelines".
Now, of course they can start blocking just about every company/user they don't care / like on twitter, but the effort might not be worth the gains at some point. And who knows, maybe you won't event be able to block some things from their algorithmic timeline, because that might defeat their monetization goals.
And yes, I realize that I might be reading a lot into Twitter's actions at the moment, but given how they treated their platform in the past year(s), all I'm seeing is that they want monetize it at all costs.
My theory is that there is basically a personality divide, probably along the introvert/extravert divide, among those who like twitter, and those who don't. Thus, those who like and use twitter frequently blame all its problems on technical details, because they can't grasp that those who don't FUNDAMENTALLY have an aversion to the push model of 140 char limited thoughts. I look at twitter and think "Random short distractions are things I'm actively trying to remove from my life."
i quite like twitter more than facebook because it's simple to use, it has really good desktop (even linux has corebird, which is quite good) and mobile clients and the asymmetric part of friendships.
Seriously I get so tired of people who don't use Twitter and can't understand why anyone else would: the product isn't meant for you.