@point5a Link aggregators were huge for a while, yes.
The main failing they all shared was being centralized services. Their growth and success inherently required increasing costs and complexity - a "vertical scaling" problem, by nature.
Federated, decentralized solutions face other challenges, but by nature are horizonal scaling models, which means they are less likely to require a single entity to spend huge amounts of money keeping things on.
@mordremoth I believe future is decentralized. Social decentralized bookmarking is sounds really good idea.