I just saw this video about Reaper 5.1:
https://www.youtube.com/watch?v=43_JHOCJvsA
At 8:22 it shows a function called "Reaper Media Item Take Envelope" which seems to be item-based automation. This function does not seem to exist anymore. Unless I am mistaken, that function was already pretty close to what Automation Items do. And it was different from today's Take Envelopes because it was not limited to Volume, Pan, Pitch and Mute. Does anyone know how that function compared to Automation Items and why it was removed?