Why did they need a browser extension to generate keys?
The extension is not essentially required for generating keys actually (though it's possible to do the whole onboarding process with the Alby extension master key lately). The extension is needed for creating an Alby lightning wallet account if one likes to do it that way. It offers to customize your name in the wallet address for free. But an extension is CRUCIALLY required for the safety of your nsec key. Thank you. 🫂
To be clear: The extension is not required to create Alby lightning wallet and @getalby.com address. It (the extension) makes it also much easier to use the Alby wallet, log in with Lightning, using Nostr. And indeed, it is recommended to use the extension to store your keys locally and sign Nostr events, instead of pasting it on every website/client. Keep #nostring!