Is it a good idea to start learning Robotics with ROS?

ROS is a tool, you can use it and follow the tutorials without being specialized in robotics, just being familiar with the basics.

BUT if you need to develop your own nodes, you have to gain a solid background in robotics, unless you need to do it the hard way with massive distractions and a lot of time wasted.

I recommend to skim ROS packages and their functions as well as the interaction between them without digging into ROS. Then start to learn robotics with ROS in mind till you reach a solid level of knowledge that is sufficient to navigate through ROS without being overwhelmed or distracted.

By doing so, you will grasp the theory and its applications.