What makes game 5 of the World Championship a draw? I was watching recently the excellent ChessNetwork  commentary of the 5th game of the WCC 2018 between Magnus Carlsen and Fabiano Caruana. The end position looked like this and players shook hands after white played g4:


[FEN "8/5R2/5bp1/3rpk1p/8/4B2P/5PP1/5K2 w - - 0 1"]


There is not much to grip onto on either side for sure, but it doesn't strike me as a draw either. The line I get with Stockfish is not straight forward.

{ [Stockfish 280218 64 POPCNT] 68:+0.00} 1...Ke6 2.Ra7 Rd6 3.Ke2 
hxg4 4.hxg4 Rc6 5.f3 Bd8 6.Rg7 Kf6 7.Rg8 Bb6 8.Bh6 Rd6 9.Rf8+ Ke6 10.
Re8+ Kd5 11.Be3 Bd8 12.f4 exf4 13.Bxf4 Re6+ 14.Rxe6 Kxe6 15.Kd3 Kd5 
16.Ke3 Be7 17.Kd3 Bb4 18.Ke3 Bc5+ 19.Kf3 Be7 20.Be3 Bd8 21.Bf4 Be7 


Is there any simple explanation why this position appears as an obvious draw other than a lack of goals to pursue on both sides?
Computer engines are of little use in positions like this. Still it is a pretty obvious draw, because of:


equal (and very limited) material
pawns on the same side of the board
no weaknesses for either player
active and safe kings


In order to win this, one would have to win material or promote a pawn, neither of which can be forced.