Because there is no need for portability, and because if they did add something to ensure portability it would come at a cost that most would be unwilling to pay.

Note that all this debugger talk is explicitly against "debug" builds. These builds are mostly unoptimized and usually quite slow. When you attempt to debug an optimized build the debugger may jump back and forth between lines many times, and will also frequently jump off out regions of assembly that the debugger has no idea where the C++ equivalent is.

There is no need, no desire, and whatever standardization were recommended would likely be ignored.

This causes me to think, is there a standard for debuggers?

Searching a while at stackOverflow.com seemed to throw no meaningful results.

There is standard format for debug information: DWARF. MSVC has it's own format that it uses. There is also a slew of front end features that are expected from people using debuggers, mostly based on gdb.