A financed buyer's lender orders its own appraisal after the offer is accepted, usually within 5 to 10 business days of acceptance, and if that number lands below the agreed price the buyer either has to bring extra cash or the deal renegotiates or dies. Cash removes that entire step, which is exactly what makes it attractive to a seller who has already mentally moved on.
Price still matters, and a cash offer that is meaningfully below a strong financed offer will usually lose anyway. Certainty closes the gap between two similar offers, it does not overcome a large one, so a seller comparing two very different numbers is still comparing numbers first.
The real advantage shows up when offers are close and the seller has a firm date to hit, since a guaranteed closing beats a slightly higher number that might not survive underwriting. Get your hand-reviewed valuation from Joel Dyck.