Personal in this case doesn’t mean private, but not customizable.
Personal views are a special view configuration type that allows collaborators with creator, editor, or commenter permissions to create views that can only be customized by the view’s current owner. In other words, only the owner of a personal view can customize that view’s filters, grouping, field visibility, field order, sorts, row heights, and record coloring.
The link you sent has the following language which indicates that others should not see my personal views. I believe that was the case until recently. There is a toggle that allows you to see or hide other people’s personal views but that Toggle appears not to do anything unless I am missing something?
“Personal views are also hidden from other collaborators’ view sidebars by default. This makes personal views the perfect tool to create tons of views to play around with visualizing a table’s data—without worrying about affecting other collaborators’ views or their view sidebar. Personal views are currently available for bases within workspaces on Pro and Enterprise plans.”
Here’s a better way of understanding it:
Airtable has no real security in the platform if you make somebody a collaborator. Once somebody is a collaborator on your base, they can see EVERYTHING in your entire base. EVERYTHING.
If you need better security, I would highly recommend checking out the MiniExtensions.com portal.