I'd give equal blame to Mac, Gase, and Douglas. (It's possible that Boyer deserves a little as well, but it's also entirely possible that he's been advocating for a better kicker behind closed doors to no avail). There should have been a second kicker in minicamps from the word go; that's on Macc. Gase staged a coup because he wasn't given enough control over the roster (his big issue, as I recall, was that we prioritized signing the two players who actually kept us in the game yesterday, but that's a separate criticism). But he and Doug each had more than enough time and clout to rectify Macc's mistake and both failed to do so.
Everyone should compete for their job in training camp, it's just smart football. The Ravens have the most automatic kicker in the NFL and even they know you bring in another kicker in training camp. (They even scooped up a free 5th round pick by doing so).