It can go both ways. It can be really helpful for people who want to learn concepts, similar to having a private tutor (but free/cheap, and available 100% of the time). But it's also easy to use it to skip the learning process completely, and just get quick answers for homework.

As an adult, wanting to understand concepts for my own benefit, I've found it really useful as a learning tool. As a teenager, I probably would have been irresponsible with it and sabotaged myself.