Methods have been patentable for as long as we've had a patent system--why should they become unpatentable because they're machine-implemented?
See: https://www.grain.org/article/entries/399-information-feudal...
(whole book: https://www.anu.edu.au/fellows/pdrahos/books/Information%20F...)
The machines, computers, are so widespread and accessible that a huge number of people are making such new methods constantly. The patent system hinges on a patent office that can reasonably assess novelty and obviousness. With software that's impossible.
I'm not saying that non-software patents are necessarily great, just that there's a clear distinction between a patent system that handles 19th century steam engines and a patent system that purports to handle software in an age of ubiquitous computers.
This is one of several intellectually honest cases for ending software patents that don't necessarily end all patents.