I'm sad I wasn't aware of this "app" when it was around. But everytime I hear about it, it is from people who "miss" it. If this is the case, then why nobody came up with a clone to it?
Check out IFTTT (https://ifttt.com) or Huginn (https://github.com/huginn/huginn). They're similar but not quite.
An underlying assumption with Yahoo Pipes was that interesting places on the Internet would offer APIs which have a developer UX that matches or exceeds the quality of their official UI. A mixture of unprofitability and abuse lead to this no longer being the case. Tom Scott's essay here: https://www.youtube.com/watch?v=BxV14h0kFs0