Umm...3 out of the 4 pre-2008 companies (Apple excepted) you listed are just as much middle-men as the post-2008 companies...they're middle men between consumer

Umm...3 out of the 4 pre-2008 companies (Apple excepted) you listed are just as much middle-men as the post-2008 companies...they're middle men between consumers (a.k.a the product) and advertisers (a.k.a the customer). The "cool stuff" you refer to is just a side effect of their rent seeking. Note that they've also displaced the previous generation of rent seekers to varying degrees (print media significantly, TV/radio a bit less significantly). Those three companies have also come with the externalities of significant privacy invasion and helping to undermine our democratic process, so there's that too. I'm not convinced that the more recent rent-seeking companies are much different than the previous generation. Both were seeking to displace the incumbent rent seekers (Uber == taxis, AirBnB == hotels, Stripe == traditional credit card processors) by finding a more efficient or more modern way of accomplishing the existing use case. The only real difference between them and Google/FB/Twitter is that their products are aimed at consumers instead of advertisers.