We should stop quibbling about the definition of an outliner, because it’s essentially a very broad one, since any text program that allows you to use an indentation level structure is an outliner, so Anytype, like Notion or programs that work exclusively with it, such as Dynalist, are all outliners.
It’s too bold and unrealistic an argument, just like this one displayed on the official website:
On the contrary, I think the borders have just been exposed. If this limitation in no way hinders your workflow, and if you don’t see the potential that its implementation could offer, then good for you, but many of us want to refer and add relations to blocks.
About that, I invite you to vote for this feature request 
→ Implement toggle for headers and hiding content