So, compared to 2x8 (or 3x8), it has:
Less gear range
thinner and weaker chain
Thinner and faster wearing cogs
Smaller chainring giving more ground clearance
One less shifter and one less derailleur
And will almost certainly cost more.
Marketing gimmick? Marketing triumph. Cut the number of components (and hence manufacturing cost), build in greater wear rates (so you sell more spares). Sell it as an 'improvement'.