It also isn't detrimental to spend time forward of the centre. That's where possessions can do the most damage. Most of the midfielders who rank very well are those who either spend time forward (such as Robbie Gray) or have the ability to impact the game heavily in the forward half (such as Ablett and Dangerfield).
But at the end of the day if you spend 100% of your time on the ground in the midfield, you'd score more points. It's why there's only 8 key forwards in the AFL Player Ratings Points top 100, even though football fan in the country would consider the proportion of key forwards in the league's top 100 to be closer to 10-15. Just because Bontempelli can point score from the forward line, doesn't mean he'd more likely score more points on average if he played Merrett or Cripps' proportional midfield minutes. For every opportunity to score goals from congestion in the foward line and gain massive points, there's 10 minutes the ball's up at the other end of the ground and midfielders are picking up points for contested possessions that don't actually achieve anything ball-movement wise. Resting forward, on team level, helps us win games and that makes him more valuable even without being measured in points.
There's also very valid debates about how the point system is "blind" how because in effect all it measures are things like possession contested/uncontested begin/middle of possession chain and location on the ground. It's poor for analysing a player's impact on wider ball movement, which is why defenders who are critical to ball movement but don't get a massive amount of metres gained or intercept possessions are not rated highly, because their contested possession rate is low. Consider this - what if a player who
correctly chooses to switch the ball in defence because he sees an overlap runner on the fat side of the ground. Uncontested -> uncontested -> 0 metres gained -> 0 points gained for the correct decision. If they make the
wrong decision to kick down the line to a pack and a teammate takes a mark, they might gain 0.5 or 1 point for that decision. This means players like Lee Spurr are rated 280th
despite fufilling the full 40 game block, because he has a low contested possession rate and metres gained, are underrated.
And then it's equally true on the flipside, it means that those with high contested possession rates are valuable without considering the wider impact on ball movement. Cripps is the perfect example of that. I say his ball winning pre-clearance and tackling is good defensively because it prevents the other team from winning the ball. But given that Cripps doesn't effectively partake in good ball movement himeslf (unlike Merrett and Bontempelli) with his high clanger, and low metres gained stats, there's no evidence that his contested ball winning helps his team's ball movement even though AFL Player Ratings Points assumes it does.