That notwithstanding, looking at the page you link, let's look at each heading and what it says.
Google Drive, Dropbox, and OneDrive integration
https://support.remarkable.com/s/article/Integrating-with-Go...
"Step 1: Log in to my.remarkable.com and click the menu in the top right-hand corner."
Handwriting conversion
https://support.remarkable.com/s/article/Convert-handwritten...
"You need to be connected to a Wi-Fi network and logged into a reMarkable account (my.remarkable.com) in order to use handwriting conversion."
Read on reMarkable
Chrome:
https://support.remarkable.com/s/article/Read-on-reMarkable-...
"You’ll also need a reMarkable account to use this feature."
Microsoft Office:
https://support.remarkable.com/s/article/Read-on-reMarkable-...
"8. Log in with your reMarkable account."
Screen Share
https://support.remarkable.com/s/article/Screen-Share
"Your reMarkable needs to be paired with the cloud"
Send by email
https://support.remarkable.com/s/article/Send-by-email
"Note: You must be connected to Wi-Fi to share files from your reMarkable. You won’t see an option to send a file if you’re not connected to Wi-Fi and signed into an account."
Tags
https://support.remarkable.com/s/article/Tags
You can tag pages without a cloud account. It's useful but at best an anciliary feature.
Limited cloud sync
https://support.remarkable.com/s/article/Connect
You need an account.