In our case, tossing stuff in the backlog to never get done is just part of trying to get through life.

We have an... eccentric colleague who demands the craziest stuff that no one else wants. Now in a sane world, we explain that his requests are either extremely costly for a minor thing no one cares about, or, like 90% of his requests, run explicitly counter to what our customers want even if we could trivially do it. He is not a customer nor is he in contact with customers or marketing or sales, he's in a different technical team but has an "armchair enthusiast" interest in my teams product.

We used to try to have that discussion to reject items to make it clear they will never ever get worked on. However whenever we did that he would demand hour after hour after hour of meeting to discuss each request that we want to reject and convince us why his requirement is the most awesome thing in the planet, and with enough meetings maybe we'd stop being so clueless and come around to recognize the brilliance.

So now we toss it in the backlog, and there's always a point of comparison like "Customer giving us $40M asks for feature X", and he has to rationally accept why X jumps ahead of his backlog items, even if he is displeased. One new project manager made the mistake of trying to close out the backlog items and the meeting invites flew about us daring to ignore his awesome requests.

So we have a chunk of backlog that every one knows will never happen, and in fact if our backlog ever dried up, then we'd have a big problem because then we'd actually have to have that tough conversation about why his ideas are bad. At this point some of his wacky stories have been on the backlog for over five years.