A lot of accountants are old school and I'd guess that most folks outside of tech are not nearly as heavily on the AI train.

Additionally, I think the industry and individual practices are probably still figuring out contracts, accountability, and legality. Will their insurance policies cover mistakes made by an AI?

I'd also guess that its one thing for you to feed your financial documents to Claude; would you feel as comfortable if your accountant were feeding it to an unknown model of their choosing? I'm not so sure I'd be.