Complaints - what's the point?

We just had an anonymous complaint which we believe was entirely malicious.  The guests arrived 3.5 hours after our check in times (1/2 hour past midnight) , disturbed our other guests and ignored our house rules.  After their visit they left an anonymous and scathing review - completely at odds with all our other reviews.  We contacted booking.com and asked them to investigate and remove the review.  This request was declined despite documentary evidence of the guests' unreasonable behaviour.

We have just received a message from booking.com asking us how satisfied we were with the booking.com response to our complaint.  I responded 'very dis-satisfied'  and the action takes us to the 'review' page of  our listing.

That's it!  There are no other instructions and no area for feedback as to why we feel very dis-satisfied.

So... what's the point?  It seems that we can just give a rating to booking.com's assistance and that's an end to it - so why bother?

It seems that, as hosts, we just have to grin and bear it when someone leaves a malicious review because, on the face of it, booking.com aren't really bothered despite all the words about caring about and supporting the hosts.