Does not necessarily means they're not good though. If those several alternatives are federated through activitypub and part of the fediverse, as Mobilizon will be when released, then strength is in the number of alternatives.

Then again Metcalfe's law has a flipside relative to the cost of exclusion from the network to those included and society, and this costs grows bigger as the dominant network grows bigger. Among the effects of such exclusion is the existence of parallel networks such as the alternatives mentioned here, and what makes them very good is that they cater to some of those excluded from the dominant network. Dark side of Metcalfe's law in action.

Had facebook not been an antisocial closed network preying on its users but open and federated as the internet has been deisgned then things would have been different, right now the problem seems to be that facebook captured a majority of internet users in some geographical areas and does everything possible to keep them captive.