Job application etiquette

In addition to the aforementioned convenience of outsourcing its recruiting function to an agency, an employer may prefer to be anonymous for other reasons:

The employer may be planning to terminate the person currently filling the job position; but, doesn't yet want the employee to find out about it, through job advertisements for his/her position, until it has procured a replacement.

The employer may not want its employees to know that it's recruiting from outside rather than promoting from within.

The employer may have a bad reputation (e.g. high employee turnover) and want to hook prospective employees with its offer before the working environment is disclosed.

*If your overall impression is that the employer prefers to remain anonymous at this stage, honor the employer's intentions. Keep direct contact with the employer as an option should you not get past the agency screening. Directly contacting the employer and/or naming them in your correspondence may open up a can of worms that the employer hoped to avoid by opting for anonymity. Use the identifying information to research the prospective employer.