Economists distinguish between non-positional goods and positional goods. A non-positional good is something that makes you happy irrespective of how much others have of it; a positional good is something that only makes you happy dependent on how you are doing relative to others. (Of course this is a bit crude. We may think of these two concepts as two ends of a scale and different people might have not quite the same idea where to put the slider for this or that good.)
On an old-school forum ostensibly centered around a shared interest there is almost always some personal drama and competing for social clout going on, but there is also often a notion of building up something, going forward, gaining knowledge, getting better at repairing cars or whatever the big topic is. By sharing knowledge, you and me can both gain. Vertical social position is not like that. If I am number one, you can't be number one.
On services like Twitter, the aspect of learning has atrophied to an almost homeopathic level, which leaves you with the zero-sum game. Prominently displayed for any random lurker from anywhere in the world to see is a number of accounts that you follow and a number of accounts that follow you, suggesting the goal of a surplus. For all accounts taken together,
1. the column with accounts that follow account A, accounts that follow account B etc. and
2. the column with accounts that are followed by account A, accounts that are followed by account B etc.
must always result in identical sums. The aggregate ratio will always be 1:1. Humanity as a whole can't receive more or less person-eyeball-time than the person-eyeball-time humanity gives.
It used to be a pretty normal online experience that one could be a big name in one place and a small one in another. A person with an unremarkable job could still be respected at least by peers in his hobby scene. More and more data gets collected, real names get pushed everywhere, and these local hierarchies and their implicit local scoring systems are fading out. And they are not replaced by egalitarianism or the dictatorship of the STEMlords, but by a totalized hierarchy of global yet surprisingly inbred elites. Not Einstein, but Paris Hilton. She can enter your hobby cellar and poop on your favorite model train and there is nothing you can do about it… Unless we go back to the old ways, the pseudonymous forums and just doing more exclusively in meatspace.