I do have problems with this, there’s no formal restriction in accounting stardards to prevent you to link an party to many accounts receivable.
But erpnext enforces that, I really didn’t know why, it’s like that since the begnning, and now it act’s like an way to be of ERPNext.
But for example, this is one restriction that complete prevent ERPNext to be compliant with Brazilian SPED (Brazilian Electronical Standards for Accounting and Reporting), since here, we need to register many types of accounts receivables/payables in they target account, with the respective party involved in the transaction.