It’s good practice to have a copy of the recovery key somewhere.
People who avoid making a Microsoft account to log on to a windows computer, or who don't have access to the email address they used can find themselves in difficulty later when windows won't boot or it wants the bitlocker key for some reason. You can't get their files off the drive by connecting it to another machine because the bitlocker key is not available.
Yes, people should have backups and copies of their keys but they very commonly don't.
If you don't sign in with a microsoft account bitlocker isn't enabled by default. When you setup bitlocker it "forces" you to make a backup of the key
* silently activates
* silently sends the key to MS.
And this is the only way to have it on home.
If you fall into the category of users that distrust microsoft with their key, you can take active action and configure bitlocker yourself.