Why are i7s not considered 8 core processors even though windows

There's no standard definition of a CPU 'core', in loose terms a core is a unit that can do integer and/or floating point operations, how it does that is and at what speed is a different issue.

>>60830415
The FX CPUs where 8 physical cores sharing a FPU.
SMT is just running multi threads on a single core in order to keep the CPU from wasting cycles.

>>60830415
>but people still talk about the FX8350 for example as a octa core.

The FX8350 is 4 core with 2 modules per core.

The i7's are 4 core with hyper threading.

The FX8350 modules are more akin to real cores, than the hardware needed for hyperthreading, while both are similar, the FX8350 is much closer to a true 8 core design because it has two modules per core, and each module itself is 90% of a CPU core.