Yeah, it has definitely caught me off guard a couple of times when installing Arch. At that stage if there's no grub it didn't install or the ESP flag isn't set on EFI. If there is grub but no options it's usually the config.
One time it was because I forgot to install the kernel, it took me a while to figure that one out.
I really like the idea of partitions without fixed sizes. I know it's not the same but just as useful when you reinstall your system.