Whether or not it's effective should be pretty easy to check since this is already legal in some states but not others. Or it should be much easier for abuse victims in the US compared to e.g. Nordic countries where corporate ownership information is fully public. Since I find no evidence of such a difference it would seem this is just the usual case of rich people using actually disadvantaged people as a cover for their bullshit.
(Though I feel like there's maybe a more direct solution to this aspect, maybe something with a nice slogan you can chant at marches...)
https://www.fincen.gov/foia-and-privacy-act-guidance https://www.fincen.gov/foia-exemptions-and-exclusions
As far as I know there is nothing special in the corporate structure that would make it difficult for law enforcement to find, the point is to stay out of public records.
I don't view these tools as being much different from VPNs. There are people that have legitimate uses for VPNs to hide ownership of traffic; there are people that have legitimate uses for shell companies to hide ownership of stuff. There are people that abuse VPNs; there are people that abuse shells. The vast majority of legitimate VPN users would be trivially unmasked by having a subpoena dropped on the provider. The vast majority of legitimate shell company users would be trivially unmasked by having a subpoena dropped on the registered agent. VPN users only become "anonymous" with great opsec and layering. Shell company users only become anonymous with great opsec and layering. The purpose of VPNs is to hide from every day people and to force law enforcement to put in work. The purpose of shell companies is to hide from everyday people and to force law enforcement to put in work. The fact that this community of all communities doesn't see these parallels is honestly fairly surprising to me.