It is not a matter of modernity, but a matter of use-case. You don't need arbitrary-length integers for a coffee machine or a fridge. You don't even need FP to handle e.g. temperatures; fixed-point is often more than enough. So if you are making some sort of "portable assembler" for IOT devices, you can safely stick with simple integers.
Of course any self-respecting modern language should also provide arbitrary-precision integers at least as an option.