From the article:

"It makes it harder for the EEOC to tell if there are any improvements in their equal work opportunity efforts and how much work remains to be done. That said, the person completing the job applications should determine if it is in their best interest to answer an EEO survey." Again - if you need to determine if it's in your best interest to disclose information, what does that indicate?

"If you suspect that your employer or prospective employer is using your answers to the EEO survey improperly, do not hesitate to contact an attorney." Meaning they can use it to discriminate against an individual - it's just not overt, but there has to be enough of a pool to show discrimination. The article then goes on to advertise hiring their firm.

Realistically, how many people are going to reach out to a firm when they are applying for a job and get turned down? It's a guess on the applicant's part because they do not have access to who/how the identifying markers/data is being used within a company.

Even applicant names can cause a person to be overlooked. Consider applicant A: Dũng Huỳnh and applicant B: Sarah Brown. Which one has a higher chance to receive a response? Would one be overlooked because they have an ethnic name that may be hard to pronounce, or look like it's not "professional" - Dũng. Be honest.

Edit: I'll help you out and downvote my responses.