As Jones noted, Mute is his "Don Quixote." It was supposed to be his first movie (he had a first draft in 2003), but it got pushed back for a number of reasons. Sam Rockwell was supposed to play a role, but Jones' insistence on different casting led him to write Moon to give Rockwell a lead (Mute is a sort of spiritual follow-up to Moon). And after that, it "kept being pushed back to the back burner" -- Source Code, the cancers of his dad (David Bowie) and wife, and other factors led him to sideline the movie and try for a Mute graphic novel that itself didn't pan out.
Netflix was, effectively, Jones' savior. He described it as an avenue for making movies that creators are "passionate about," rather than"homogenous blobs" intended to cater to absolutely everybody. The internet giant thrives on niche productions, and was willing to take a chance. It certainly helps that Jones is an accomplished filmmaker who can bring well-known actors to his work, but it's clear that Mute's odds of release wouldn't as been as high if Jones had pushed for conventional distribution.
Netflix clearly has reasons to be optimistic about Mute's success. The streaming giant has been making a big push into exclusive movies with top-notch talent, and that strategy has already paid off with the success of Bright. It doesn't always need blockbuster viewership -- it just needs enough interest to recoup its investment and draw in would-be subscribers. Should Mute be even modestly popular, it could also attract other directors who feel that theatrical releases have too many creative and financial hurdles.