You are correct here, there is more than one way to play position. However the critical aspect is that way of playing the position needs to compliment the rest of the team.
For example, if we were a team that aimed to put 50 crosses into the box a game but our centre forward constantly held a position outside the penalty area would you be making that argument? Of course not, because it obviously wouldn't compliment the team.
Much in the same way that having a goalkeeper who hates leaving his 6 yard box is not complimentary to a team that wants to play the game in the opponents half of the pitch. If we still defended with 8 players like we did under Mourinho, his limitations would be less of an issue because there would be more players back to a) stop the cross and b) deal with the crosses into the box.
As it is, we have signed offensive minded players and as such we are more open to being counter attacked upon, which is where him needing to sweep a lot more than he does comes in. Also, there are less players back in defensive positions when balls come into the box and as such you need a more commanding presence to help out of the defenders because the centre backs tend to just get left alone to deal with them. In addition to this, we have been signing defenders such as Maguire, Varane, Lindelof who are used to playing in front of dominant goalkeepers and instinctively they look to the goalkeeper, it is there for all to see. There is a clear disconnect in styles and ultimately yes, it is a hindrance to the team.
