What are the arguments against a host and guest booking directly, instead of through services like Aibnb, VRBO, etc? I stayed at a house successfully for a wee

What are the arguments against a host and guest booking directly, instead of through services like Aibnb, VRBO, etc? I stayed at a house successfully for a week last summer, and the host and I are interested in re-booking for next summer (same guests, host and location)? Any reasons why host shouldn't book directly? Any reasons why I, as a guest, shouldn't do it? Obvisouly, booking directly would save about 15% in transaction fees. Thanks!