Perhaps the @moderators could split off here since it is kind of the opposite of the OP’s topic.
I know @Jhana4 you were just giving a hypothetical, but it’s kind of outrageous to think that if someone asked a monastic if they needed anything they would be told that the monastery needed a new heating system.
I’ll also admit that I have always “filled in the blanks” when I read that sutta assuming that if the donor either mentioned immediately that they could not provide what the monastic asked for, or if they followed up in a timely manner informing that they could no longer fulfill the offer, then the karmic consequences would either not exist or they would be reduced. I realize that others may not agree with that kind of “sense making” reading.
But the opposite does happen that people make a good faith request and then don’t come through. Or that it takes them a long time to fulfill without any followup. Not often, but it can happen. Then, as Ven. Suvira mentions, the monastic is kind of stuck because they don’t want to mention the need to anyone else for fear of getting it twice or the original donor somehow finding out. And it’s super akward to go back to the original person and say, “hey, how 'bout that offer you made.”
I think the other teaching we get from suttas like this is on the side of people wondering directly why they aren’t able to succeed in their plans, not just as a caution to potential donors. When people can know that the results they are experiencing, both good or bad, are because of previous actions, then it can increase faith.
Likewise, when someone has done a good job at giving, their joy increases knowing that they have done the action to the best level possible. This increases joy in the practice.
The sutta also has to be seen along side the other suttas that condemn monks who don’t know any limits when invited. E.g. MN33
And how does a mendicant milk dry? It’s when a mendicant is invited by a householder to accept robes, almsfood, lodgings, and medicines and supplies for the sick, and that mendicant doesn’t know moderation in accepting. That’s how a mendicant milks dry.