The traditional thinking is the client should use all of the tax-deductible tax-favored vehicles available (like qualified plans) before using after-tax fax-favored vehicles (insured private pension plans, tax-deferred annuities, etc.).
However, qualified plans come with a price, namely the cost of covering other employees and administration.
After-tax tax-favored products come with a price, namely being limited to the insurance product offered. (Qualified plans have "almost complete" investment flexibility -- "almost" because certain investments like collectibles aren't allowed.)
If the ONLY FACTOR is maximize the owner/minimize everyone else, then I agree that there comes a size where the qualified plan route isn't the most advantageous. Probably when 50% to 75% of the contribution goes to the owner is that point (as indicated in the article).
However, the value of the client's business is perhaps his/her largest asset. To the extent they believe that providing benefit to their employees enhances that value means that we shouldn't ignore the cost of providing some benefits to employees. (Of course, it is entirely the client's call. If the client believes that employees are a dime a dozen, then the pension plan, if any, should reflect that belief. If the client believes that employees are valuable, then the pension plan, if any should also reflect that belief.)
Also, the article indicated that 85% of Fortune 500 companies have non-qualified pension plans covering their executives. Of course, they have qualified pension plans covering all employees (including executives), as well. The Non-qualified plans are a supplement for the executives.
Now, since the private pension plans are funded through a specially designed high quality insurance product, according to article, I would ask why these products are not the mainstay of the qualified plan arena?