Rather put recruiters on an Ignore list then if no indication is done. Generally, and in IMO, if salary isn't mentioned, the company recruiting wants a slave.
I know this response is old but I think it's worth mentioning the below.
Let's say a company has many developers and they open another development role through advertising. One of the currently employed developers sees the posting and that it is offering more than they are earning (this can happen for many reasons), then you as an employer will now you have a difficult HR situation. It's a well known fact that companies ask employees to not discuss their salaries as it can create colleague and company tensions. Do you discuss your salary with everyone at work?
While I'm also not a fan of a job posting not displaying a salary I do understand the psychological aspect. Logic does however dictate that the required skills should match the industry standard. If the job is for a highly skilled employee or management role then it may be worth posting a salary range but for anything less I don't think it's worth it.
If a job posting has no salary then it's as simple as emailing and asking the remuneration budget. If this is too difficult then I can only assume the applicant is a lazy millennial.
Another thing to think about is a job posting for an executive. What kind of issues would that create if employees knew their salary? I know all too well from personal experience the chaos that it creates when employees find out what execs earn.