That one technology worked does not automatically mean any other technology will. There is no argument that begins "A worked and so B will too". Also, email is pretty much dead as a technology - it's just spam and password reset emails at this point.
I think parent was not saying new tech will succeed, merely there is an extended hangover/negativity due to recent busts.
Regarding email - it's probably one of the most used bits of technology in existence, and I bet it has a similar OOM economic impact to something like Excel. Calling it a dead technology is not accurate - so much business is done via email, especially internally at SMB.
