It's wise to work with accountants, but it's not enough. There are a lot of characters in business, and in order to know when they're full of shit (because sometimes they don't even know), you need to know how to count beans by the rules.

For example, a public company might report itself as profitable for some period based on operating earnings alone. But, you read their annual report and see they took a loss after tax with some extraordinary items. If you don't know what that means, then you don't know what it means--It really means they didn't make any money for the period, but they're going around talking about it like they did. I should mention that's all elementary stuff--there exists a whole field called "Forensic Accounting" where accountants work to spot fraud in financial reporting.

And small business owners can get mixed up too. They talk about their big revenues but don't mention they have a lousy 5% net margin. It can extend beyond trying to bullshit you--they can get into the habit of bullshitting themselves thinking they're ballers.

I don't think he's saying " it is not wise to have someone specialize in it for you", he's saying that that isn't "good enough". Ergo, you need to have a solid fundamental understanding of how money is processed in a business as well, in addition to having specialists handle the things beyond your level of detail.