As a young apprentice, it used to irritate me or stress me out when I'd left my homework until the last minute and the senior engineers around me wouldn't serve up the answers. Surely they were being obstructive - difficult - delighting my downfall, because I'd done nothing all week then started an hour before the deadline.
They always patiently gave the same reply: "If we just tell you the answer, you won't learn".
What I slowly but surely saw through practical experience was that they were absolutely right, spot on. Since then, I've had a great deal of time with more inexperienced engineers than myself, some younger some not. And plenty of cleverer ones than me :-)
I've found that advancing people through possible directions, steering them gently to sounding out the solution for themselves has turned into skills, capabilities, enjoyment and satisfaction far more often than not. It's very rewarding and I enjoy taking the time for others that others put in for me. It's not 'my' knowledge - others gave it to me and now I'm passing it one to more people. All these people were us once.
So I genuinely believe that just serving up answers does not directly produce OPs skills, capabilities, enjoyment and satisfaction.
I do understand clearly that sometimes decent OPs really don't know where to start and will really benefit from being walked through something. We all do and that's perfectly normal in these potentially great engineers. But you can very often tell such a good 'un in their responses in comment exchanges.
Serving up answers would make the site appealing to the lazy, those not bothering, and I can't see how that would benefit the site. A few users enjoy pouring scorn, derision and shouty bold text on such people, so fuelling their rage won't benefit them or the site either.
It's good to see OPs encouraged to explain their question, put all their thought and effort into what they understand so far. I notice that a few just fade away but many really pour their effort into a good post or a good revision of it and that's admirable to see. That attitude breeds good engineering.
Onto your actual question...
I've long thought about a VTC 'homework' option. I think it'll get badly misused. And some of our harsher members just firing off 'lazy homeworker', without looking into if help is needed, will alienate many users who may feel patronised or belittled.
Meanwhile, there are users who'll post an answer to a homework question out of a genuine desire to help or to get easy upvotes.
(a) FOR QUESTIONS: I'd stick with having to VTC with a comment, to make it harder to write that reply.
(b) FOR ANSWERS: I would like to see a flag for answers for a nicer phrased version of 'rewards lazy question'.
However, the mods would then have to follow through and really crack down on (b)-flagged answers and some mods understandably have a different policy on deleting answers. And the OP could still read and benefit from the answer before the mods get the chance to respond to the flags.
What is really needed for (b) is a way of sending discouragement to the answer posters. At the moment, that's by comments and downvotes. The latter reduce the objecting user's reputation and so some users are reluctant to do it.