Its not about 'doing a Leeds'. For example, to make it simple let's say Man City say Savinho can only leave for £130m - should we pay that? It's not our money, who cares, right? But if we pay £130m for Savinho, then we most certainly won't be getting Eze as well, or anyone else this summer for that matter. So anyone who believes that the club is cautious with it's money - and surely most fans do believe that - should not be wanting us to 'waste' money or pay more than a player is worth, as that reduces the amount that we can spend on other players.
(I know the numbers above are ridiculous - deliberately so in order to make the point easier to understand, given people's apparent 'struggle' on this topic

).