Google/Facebook/etc users well know that they can use the "Login with...", and spot them immediatly because the button is graphically recognizable and tied with the company name. No need to know all the tech background.
Given that "Login with nsec" is bad on all the web contexts, and maybe also for apps in the future (we will have signer for that), why add another brand when we have "Nostr"? It only dilutes the effectiveness.
Nostr is both a protocol and a social/functional layer, you need to know that it exists, you cannot hide it.