The 6502 is actually still in production. However...
Modern assembly x86, or even modern ARM assembly, is significantly more complicated than 6502 assembly.
Starting with the 6502 will let you write working code more quickly and introduce you to the core concepts of assembly language programming.
More than this, even if you never write assembly, being aware of what a CPU instruction set looks like helps you grasp core concepts in C/C++.
If you're only ever going to write high level code (e.g. JavaScript) this probably isn't helpful. But as an aid to understanding how computers work, and what they are capable of, it can be really useful.
Modern assembly x86, or even modern ARM assembly, is significantly more complicated than 6502 assembly.
Starting with the 6502 will let you write working code more quickly and introduce you to the core concepts of assembly language programming.
More than this, even if you never write assembly, being aware of what a CPU instruction set looks like helps you grasp core concepts in C/C++.
If you're only ever going to write high level code (e.g. JavaScript) this probably isn't helpful. But as an aid to understanding how computers work, and what they are capable of, it can be really useful.