I'm not sure about that. When all the SSPs are run by one entity, how self-custodial is it really? Sure, you can unilaterally exit, but that's only a small benefit.
Privacy-wise it's much worse than LN, because it operates with similar properties as the main chain. You're going from trusting one LN custodian to trusting another LN custodian LightSpark) on a much more transparent/trackable chain.
I really want to like Spark (and Ark), but it doesn't seem like its glaring and serious issues are addressed yet. Until such time I advise everyone to stay away from it.
It rather seems like everyone is pushing Spark because it's easy, and legally qualifies as "self-custodial", so gets around Google's recent KYC requirement.