ASBMs, or more specifically, DF-21D and DF-26, is a game-changer. It's an innovative way to integrate medium or intermediate range BMs with various C4ISR assets to hit moving targets in the ocean, something that has never been done before and is difficult to do. They pose a threat to aircraft carriers within their effective range, thus potentially reduce the effectiveness of the carriers, something that other means are difficult to achieve. Aircraft carriers are the primary power projection platform for the US, particularly in the Western Pacific where basing options are limited and geography is more challenging.
Clearly, the USN takes ASBMs threat seriously. Let's at least admit that. The USN or other navies that have felt the threat are understandably working on ways to deal with the threat, whether that is SM-3 or SM-6 or other means. Over time, they may find ways to better deal with and reduce the threat of ASBMs. And then the cycles of improving spears and improving shields will continue.
To me, the fact that the USN admits and takes ASBM threat very seriously and China displays them very publicly (and has invested heavily in the R&D of ASBM, as disclosed by a lot of research papers in the area) are evidence enough for me they're not just smoke-and-mirror. They're real weapons.
Now, it's fair to question how effective these ASMBs are in a real battle-field environment, because after all they're not battle-tested. But I don't think the USN believes they can handle the threat with 100% confidence now, or China believes they can hit a carrier with guaranteed success (it's a probability thing). But isn't this also true for a lot of weapons developed during the cold war?