The decision to force you to sign in to view replies is clearly not by accident or ineptitude. It's probably not malice either - just a business decision.
A business is free to choose that you must login to access their content and you are free to choose not to do business with them if you don't like it. I generally chose the latter
Either way, I don’t care. The Internet has become so hostile to users that the only moral and rational choice is to not participate on platforms that have become so hostile that threatening legal action is the only way that they can protect their relevancy in facilitating social discourse.
It's all about getting people locked into walled gardens. I wish the EU DMA had taken a harder stance on this and required all social media to federate to some extent.