> It's easy to say that "Slack solves the problem of centralized team communication" or "eBay and Etsy help everyday people collect money off their trinkets, crafts, or useless old clothes".

I would also say that if you'd told people about those problems thirty years ago, people might have responded 'but I can already communicate with my team using a conference call' and 'I can already sell items through the classified or flea market'. 'What new problems are these things solving?'

I think that most inventions don't do anything particularly new - the kinds of individual tasks you can do with them could have been done before. What they tend to do is provide greater efficiency. And greater efficiency at scale enables new kinds of things to happen.

E.g. think of youtube. It was possible for people to share videos before the internet. E.g. you could have submitted a description of your video to a printed catalogue, and if people wanted to watch it they'd contact you via the catalogue, so you could send them a copy on VHS. What youtube and the internet does is makes it so much easier -- so much more efficient -- that it makes it practical, and the scale enables all sorts of new things to crop up on top of it.