Blame the manufacturers for not including hardware security on cheaper phones. It would be nice to not have to pay a premium for sufficient security, or to have sandboxed Play Services on a less secure phone for example, but it's simply not GrapheneOS if you gut a lot of features that make people trust in it. That's not GrapheneOS's fault.

Same principal as Privacy Guides. They're not going to recommend something that's doesn't meet their requirements. You will not see them recommend Windows no matter how many people comment "but how do I use Windows privately?" You can't. That's why it isn't recommended.