HBO has always stood for premium entertainment for adults. There are other sides to the brand, for example children's programming. Ultimately premium programming is the biggest pull of HBO, not the other stuff. By naming the streaming service meant to convey the whole of Warner Bros. catalogue, and now on top of that Discovery as well, is a mistake. It enlarges the brand too much, too quickly. It puts under the umbrella of HBO things that people do not associate with HBO. Porky Pig cartoons don't fit under HBO. Discovery's wall of cheap reality TV even less.
A counter-argument is Disney. Disney+ includes a ton of things that are traditionally not associated with the brand. But I say that it no longer applies. Disney has successfully enlarged their branding, you just haven't fully realized it yet. That larger umbrella for the company was built over two decades, and cost billions. It was built on the back of Marvel and Lucasfilm. HBO is not there yet.