What made the 2015 Giro work was the dynamic with favorite with a terrible team who also wasn't dominant in the mountains, and there was one team to shred everything because they needed to attack. Basically imagine Vingegaard doesn't drop Pogacar until Hautacam.
In terms of mountains though, I really agree with the idea that the near 0 emphasis on MTF in the 2015 Giro was great. Even if you were easily the strongest climber, you had to make crazy attacks to make up for the TT losses. The 2016 Giro also didn't emphasize MTFs, and it had great mountain stages as well.