Yeah, for all the existence of
the blurb at the start of the Sage Advice documents that discusses RAF and RAI as well as RAW and that they will provide all of those, Sage Advice has given RAI and RAF interpretations
very, very rarely. You can tell they never do this because they almost never answer a question with, "This is what it says, but it's not what we intended at all." Simply put, I do not believe it's possible to write the books remotely that error-free. There's a couple examples where they do this, like the question about Druids speaking while in Elemental form, and one other about wild shaped Druids being disintegrated, and another about how conjure woodland beings is supposed to work. Others, like the ruling that Crossbow Expert was
intended to work on spell attacks, and that spells that target creatures really are intended to
only target creatures, or that Archery fighting style intentionally doesnt' include thrown weapons, each really strain credibility that this is the intent and not just what they published. Most of the time when they discuss intent, it's really, "Is this the literal reading of the rule?" "Yes, that's the literal reading of the rule."
Mearls would do RAI/RAF answers and would answer with how he would rule like Gygax did, but they don't let him do it anymore because Crawford would contradict him too often. Essentially all Crawford ever does is read the book back to the person who asks the question with
the narrowest possible reading regardless of the game's history or logical consistency between different mechanics. That's exactly the kind of readings they used in 3e and 4e that they supposedly intended 5e to avoid. It makes sense that he does that because the Internet has
certain kinds of people on it, but I don't really find a book reading service to be a net positive for the game.
It was that realization that made me realize that Sage Advice exists solely to pander to the set of players that are upset that D&D doesn't have strict templating and regular phrasing like M:tG does. I don't think it's wrong to make a TTRPG strictly templated like 4e or M:tG is so I do not mean that disparagingly, but 5e D&D was very, very clearly written to
not be strictly templated. D&D 5e
wants you to read between the lines and to ask your DM how they interpret it and to have a discussion at the table. In that sense, I think that Sage Advice as it exists today is probably the worst part of the entire product line as it essentially actively undermines the game's core philosophy.
The only purpose I can come up with is that they didn't want spellcasters to be able to cast a spell and still take the bonus shove action. That's really quite narrow, however, and I think they're somewhat overestimating the power of the feat. I agree that they probably should have written, "When you take the Attack, Dodge, Dash, Disengage, or Use an Object actions...."
I really dislike this idea that while you can mix your move into your action however you want, you may not do the same thing with your bonus action. Or that if you have to do something to allow you to take a bonus action, you can't do that action after the bonus action. Or even the idea that you can't take the attack action if you don't have something to attack. It seems like unnecessary complexity for the the rules to care about. It's essentially never a good idea because it's so expensive action-wise. So why bother banning it? It's needless rules weight.