Comment by shiohime

I've been working on Solana and Ethereum dapps and it does rely on browser extensions at the moment (MetaMask or Phantom wallet for example). But basically they expose an API that lets you connect a wallet. In one app I'm working on right now in Solana, I'm able to connect in a one line api call (granted if I want to support other wallets I'll need to use an adapter npm module). Since you need to have the private key to set up a wallet, connecting is essentially "logging in". So really, I can make a website that lets you use a wallet with no money on it as authentication, if I wanted to, since it proves you are who you say you are unless your wallet's private keys are compromised.