Agreed, it would make hosting a comments section where you solicit contributions from the world at large somewhat less appealing. However a self hosted federated social media protocol such as AP or ATProto isn't substantially impacted. Under such a model your blog can still have comments you just can't host those comments yourself unless you're willing to assume some amount of risk (probably not much in practice TBF).

As such I'm not convinced that anything of value would be lost. That said as I've stated in other comments I'm also not in favor of that.