In a well designed sump (water treatment "plant"), you will have various compartments for specific functions. So the straight forward idea and the natural thing would be to house whatever equipment doing a specific task in there (rather than to divert some pipes with pumps and all, all over the place which will become messy).
1st advantage - less messy, if containment is all within a well-designed sump.
2nd advantage - should there be any leakage (in equipments and all) it will be contained within the sump.
3rd advantage - Some equipments that will be house in-sump need no feed pumps and all whereby it will save on pumps running cost, cost of pumps, heat from pumps.
4th advantage - simplicity is a key to a straight forward success.
5th advantage - containment within the sump saves additional space needed by outsump equipments.
The list goes on...