Tragically, when you are organisationally impaired from saying 'no', this is the only way (besides, you know, quitting and getting a new job).
It's absolutely soul crushing when you're motivated to do a good job, but have a few colleagues around you that have differing priorities, and aren't empowered to do the right thing, even when management agrees with you.
I am both an open source maintainer and contributor. This is absolutely despicable behavior. You are purposefully wasting the time of a contributor for no other reason than your own fear of saying “no.”
If you’re not going to merge something, just ficking say so.
Wasting the time of someone who put no effort whatsoever into their work and wants you to put in a lot of effort? Fine by me.
If you've read the thread, the strategy you're replying to is about a workplace scenario where outright rejection is, for whatever reason, forbidden; not an open source situation where "no" is readily available.
It makes even less sense in a work context either. This behavior will permanently alienate this user & potential customer. I’ve seen this exact scenario play out many times before.
As long as the response delay increases at least geometrically, there is a finite bound to the amount of work required to deal with a pull request that you will never merge.