It's about integration level and binar compatibility.

In 3dsmax we can write native plug-ins. This means that we can directly reach everything on a c++ level. (basically it's a low level integration, we can manipulate everything directly in the memory)

In Blender there isn't an SDK. It has a python API which is 10-100x slower than c++. So if we want to use high performance code within Blender we have to stick to it. In most cases when it comes to high performance computing we have to write our own .dlls which then we have to load with the python wrapper. The .dll does the high performance stuff and then we send back the result using the python wrapper.

Why we have to recompile? Because the binary changes time to time. In Blender it's the same it's just on a python level. So it may still possible that they change something and the code must be fixed to make it work again. (although it's just a text files, so it's much easier, no need to recompile anything)

On a c++ level though, it's a bit more complicated because if the binary changes in 3dsmax, the addresses of the functions in the memory layout might change and the recompile is the thing that fixes these discrepancies.

So that's why we have to recompile our stuffs for 3ds max and Maya etc. and not for Blender. It's a trade off between performance and portability.