consider that the rent bill should be able to not be simplified with the rest of the bills
When living with a group of people, it is common that one person pays the entire group's rent, and the other members pay their share to the one. We do not put rent on splitwise because splitwise simplifies rent, along with the rest of the expenses (the whole point of the website pretty much), but since rent is such a large bill, the one who fronts the rent wants that exact reimbursement in an account devoted to paying rent, therefore he does not want rent to be lumped into the other debts.
In other words, give the option to set certain (recurring) bills to not simplify with the other debts.
Example, I pay $600/month in rent to one person every month no matter what splitwise records show, and then allow for the simplified splitwise debts separately.

This is definitely a legitimate problem, but it’s not one we’re planning to solve in the near future. Right now we’re making an active effort to simplify Splitwise, and adding a new special option to recurring bills doesn’t quite fit with that plan.
For now, if you’d like to treat rent like a separate account, it’s probably best to actually handle it that way, either with a separate Splitwise group or offline. Sorry for the trouble!