Are you referring to the online courses that are simultaneously providing the output of the code as soon as it's written? If that's the case, it's not really helpful as people do obviously need to test it out from scratch, on their own for a better understanding of how stuff works. But this method is easy and fast, provided some hand holding is needed and if that support is there, one can learn pretty quickly.

The need to emphasize breadth-first learning in order to do anything in a modern web stack means that they not only never learn anything in depth, they don't learn that a modicum of depth is necessary.

They don't get taught to conserve memory...

Java

...and the whole JavaScript monstrosity