ERC20 is not friend with ERC165?

Hello fellow shadowy super-coders.

I am wondering, why ERC20 token doesn't implement ERC165 standard? I know it's not mentioned in the EIP, but basically any other token standard does mention that. It would be very useful for protocols working with more token standards. Currently, they can rely on ERC721 and ERC1155 implementing ERC165, but for ERC20, they have to find another "hacky" way.

Also ERC20 token is not plain ERC20 anymore as it implements increaseAllowance and decreaseAllowance functions.

Is there a particular reason? Has it been discussed before?