Just so you know, terminology matters greatly. There is a login and seed phrase for Brave Wallet. The term you’re meaning to say is no login for Brave Rewards. But even then, that’s only true if you haven’t Verified your Rewards with Uphold or Gemini.
There are FAQ and all which warn about reinstalling and how to backup your BAT. For example, the one I wrote and is available here on Brave Community. You can read it at -Retired- PSA: User FAQ - Support & Answers
NOTE
There’s too much to talk on in regards to why things are the way they are. I’m not even going to go there. What I will tell you is this:
Rewards backup is coming. The way they are doing it is actually moving Rewards over to Brave Wallet. They are hoping to finish things in development at the end of this year and then to release it to everyone in the first quarter of 2023. By it being on the Wallet, then Rewards will be saved so long as we keep hold of our seed phrase. You will still have to verify with a custodial partner, such as Gemini or Uphold to withdraw BAT outside of Brave, but it will at least be safely kept in Brave Wallet so it’s not lost even if you reinstall Brave (so long as you have that phrase).
But yeah, again, that’s not until early next year. Until then, you have to do backups of Brave or make sure you’re linked with Uphold or Gemini so you don’t lose anything.