That's kind of the point. Security teams have stopped doing any risk assessment after Heartbleed, and now all it takes is a pretty website to have a "real" vulnerability

This may have caused some unwarranted heart attacks lol

Thanks, I changed my bank account to have 100 million dollars with that one weird trick.

Not directly. UEFI itself only supports mounting a minimal set of filesystems. That's why your EFI system partitiion needs to be FAT32, for example, and why the kernel and initial ramdisk are also located there. UEFI mounts the ESP and executes the bootloader, which then loads the kernel (located at ESP/vmlinuz-linux on Arch) and initial ramdisk (ESP/initramfs-linux.img) into memory. The initial ramdisk is a compressed image of an early root filesystem that contains the tools and drivers necessary to boot the full system, including the filesystem drivers for ext4/btrfs/whatever.

You could build an EFI program that natively supports different filesystems, though.

I mean you can easily edit grub at boot and boot straight into single user mode without logging in.

Well that is exactly what chroot'ing is, loading up another linux instance so you can modify the local (usually broken) one

This is intentional behavior as you need physical access to the drive, and most sensitive information is either encrypted by your application(keyring, password manager, password protected files, etc), or you can choose to encrypt your whole drive