I wish I had a different opinion so I could write some countering arguments but I largely share your opinion. I am amazed by the technological advancements recently but I don't think they are only possible with a concentration of capital and knowledge in such companies. I believe that the open source community could have made major advancements as well, but sadly there isn't as much money to be earned as an open source developer. And while the means of tech companies speed up the development process extremely well, I think it would have worked without them as well.