This is gonna be a medium to long read, so if you want the tl;Dr - such system has no safeguards against abuse, and will further thwart the number of honest, negative or less-than-glowing reviews. As well as it will ostracize clients who have higher standards and are tough graders.
Let me preface the actual discussion of the proposed system by stating something that should be semi-obvious - as reviews influence money sellers are getting, it is generally within the sellers interest to silence or invalidate negative reviews. The incentive to do that is large because it is a direct monetary gain.
On the other hand, incentive for a client to write such a honest, negative review in this biz is a magnitude lower. Simply because there are far more issues he (or she, love ya lopaw) is bound to run into writing such a review than a positive one, from provider bl to angry provider stans, etc etc. The biggest incentive is really warning the next client, and that incentive cannot compare on the proverbial scale when balanced against enticing monetary incentive by the seller. When money and being fair/idealistic are on the same scale, it is clear what will weigh more.
So it's fairly obvious to assume here that some percentage of sellers - if they have an opportunity backed up by incentive - would abuse such a system so that they are viewed in a better light.
So let's start from the beginning. Current system isn't ideal. Many sellers complain about turnaround of review dispute. This isn't ideal, BUT something that is often glossed over is that time as well as complexity both serve well as a deterrent of abuse.
Let's say a provider sees 20 negative reviews she/he wants to dispute. If they know if it will take 5 days of back and forth for each instance with typing up explanations, that is a lot of time. They would take the most egregious ones, if any, and won't bother with other ones.
The amount of time they'd spend disputing these reviews for a chance of those reviews to be delisted is worth a lot of money. Possibly way more than they'd gain.
However, if let's say we had some tech that you can just rate your own review you don't like as "1", seller can then rate all of these 20 reviews in under five minutes. Just by doing that, they improved their chances of making more money. So why not do it all the time then? If you can in fact make a review seem less authentic to other mongers, these five minutes of downvoting reviews turn into some of the most efficient ways to pump up your biz. Five minutes of "work" is worth it even if it gets you an extra trick, let alone 50 extra tricks. Fifty tricks at modest 400 an hour we'd have 20k profit off five minutes of "work". Why wouldnt every seller do this?
We can project what will follow pretty easily.
The negative reviews will be downvoted to the core of the earth. And many reviewers will stop writing legit negative reviews so as not to fall to the "untrusted reviewer" moniker.
Giving the seller an ultimate ability to rate their own reviews with global visibility is just a not good idea in general.
And the problem is, any safeguard I can think of - such as putting limits on rating reviews, requiring extra communication and review, that would serve as a deterrent of abuse, will just make the system more complicated and hard to follow, or will not achieve the same result as wanted.
Id argue the "like" system on ter reviews that is present currently does a similar or better job even if bugged (you cannot take back a lkke even when you liked smthng by accident). It is not limited to sellers either, anyone can like a review for whatever reason. Certain other sites that review let's say amp storefronts, enable comments in reviews that allows people to comment on reviews, however a lot of times disputed reviews back and forth become ugly.
