That has never been a good argument, but today it's absurd. Even when losses are insured, the business still loses. Coverage is normally limited to cash value of tangible items. Downtime, loss of customer goodwill and of future profits are may not be covered by standard policies. And, rate increases are almost certain to follow any claim.
Every business needs a loss prevention program.
The nature and extent will vary with individual requirements but some type of program is always necessary. Loss prevention is a critical management function.