لأنها في غاية الوكادة سببها
Its underlying legal basis is strongly emphasized.
The binding force comes from the law's commands and prohibitions, not from the person's preference. A person is accountable to the original divine ruling; this provides the starting point for understanding any later concession.
For example, a prohibited act already has a baseline ruling. If a serious excuse later arises, that does not mean there was never an original prohibition. Rather, a concession must be analyzed in relation to that pre-existing ruling.