Comment by drillsteps5

I honestly don't know if it was sarcasm or if you were serious.

At any rate, the downside of this is as follows.

The goal of having Human Resources, talent acquisition, recruiters, and other similar roles is to let hiring managers (and everyone above them, up and including the CEO) concentrate on doing their job and only assist the aforementioned roles in hiring. Of course hiring manager is ultimately responsible for hiring a good candidate but they are not expected to do things like posting job descriptions, initial screening, background checks, referral checks, employment history verification, dealing with legal stuff like NDAs etc etc, that's the job of HR/recruiters. Candidates reaching out to hiring managers (and especially higher ups) are not treated nicely by the HR as these candidates are attempting to take HR out of the picture.

HR are people and want to keep their job and get paid, and you circumventing them might be perceived as a threat to that.

That IN ADDITION to a disruption you will be causing hiring manager (or especially CEO) cause now they need to decide what to do with your email. Even though they have HR/recruiters to handle these things.

A typical result of such a "reach out" will likely be forwarding this email to HR and subsequent rejecting/blacklisting the candidate.

Edit: some clarifications