Some send over X amount of sales and want an explanation on why each wasn't included in the report.
Which is allowed...though there should be a logical limit to the number of sales, IMO.
Others send over a sale or two and and want it included in the grid even if it is given no weight.
Asking one to include such sales in a grid (as opposed to just addressing them in commentary if they are not relevant) is a pretty clear AIR violation. It also puts the appraiser in the position of contradicting the certification, which states that the best sales have been used.
I do believe that some handle ROVs this way - I also believe (because I have seen it first hand) that SOME appraisers interpret a request to comment as a a request to grid. (not directed at you, DTB, since you clearly distinguish between the two in your post) I even called a guy once and asked him why he gridded certain sales. He said, "Well, that's what I was asked to do." I pointed out to him that what he was sent did NOT say that

He agreed after he read it again.
So what is the point, if not to exert pressure on the appraiser?
The point is customer service. As I said before, lenders know that in most cases the appraiser has done his/her job, and the ROV will not change the results. They also know that even if they don't make the loan, there is always the chance for another loan down the road. So, they try to appease a potential future borrower (who is very likely upset).
Anyone who reads this forum on a regular basis can quickly see that there are many appraisers with very little sense of, or interest in, customer service. They want to get an order, do the appraisal and be left alone. No updates. No calls. No follow up of any kind. Just leave me alone and send me my damned check!! Again, see prior comments on business acumen. Many of the lenders we work with also do direct engagement, and as I speak to those lenders who deal with appraisers directly, the number one complaint I hear is the general lack of customer/client service. Want to build up an appraisal business? Just applying the customer service principles that most companies in other fields use will put you far ahead of the game as an appraisal business.
And, before anyone goes there, customer service does NOT mean cowtowing or rubber stamping values. It simply means treating a client like a client, rather than a nuisance.