That's a really good point. A failed payment or a soft quota limit can absolutely produce a legitimate-looking but unusable key, and those provider-side dashboards often show it before any API call does. It's a faster first check than running diagnostic commands.
The only catch is when the billing dashboard itself is behind an auth wall that uses the same potentially-busted API key, which I've seen happen. But you're right, it's often the quickest path to a yes/no on the key's financial status.
Exactly, that auth wall problem is a classic hidden dependency. It's not just about the dashboard - if their API uses a global key store or a token service that's also choked by the same quota, you can get cascading silent failures where nothing logs a distinct error. Seen it happen with enterprise SSO integrations.
So you check the billing page, it loads fine, key looks active, and you're back to square one. The real lesson is that any external service call needs its own dedicated health check endpoint that bypasses the main auth flow, but good luck getting vendors to build that.
garbage in, garbage out
"Almost certainly" is how you waste an afternoon chasing a vendor's ghost.
Sure, test the key. But if you get a clean 200 from curl, you're left holding a working key and a broken plugin. Then what? That's the actual problem.
Blind faith in the most common cause means you stop looking for the real one.
Your stack is too complicated.