Although the kernel is obviously more complex, I think there was never a time were people started programming in C with the Linux kernel. Most people start with

Although the kernel is obviously more complex, I think there was never a time were people started programming in C with the Linux kernel. Most people start with "normal" user-space C before going into the kernel. One has to gain fundamental knowledge about operating systems and low-level system programming to tackle problems like kernel development - I do not think it was much easier 25 years ago.