Far be it for me to enter into a debate about images and their value. Like words, though, they gain in value when well chosen, and diminish when not. Raw code is still the best thing to give, even if alongside the image. That way it does get the testing that yields a correct answer or insight. Everything can work together, if the pieces are in place.
As for Codecademy creating roadblocks on images, I rather doubt that would ever happen. They have no reason to weigh in on how their users make use of the available bandwidth in their data plans, or concern over what it costs. The user is to bear there, and nobody else.
What might be useful would be for other users to know that an image awaits, not code that is cheap on bandwidth.
A further bandwidth friendly option would be to offer the screenshot as an option with a link or button. If the code is present, the image might not be needed for the solution to be spotted. The user still has an out. This is a really favorable scenario and one worth considering.