Claude Shannon huh?...

You generally don't get a first job in IT as a System Administrator, ever. Its one of those unicorn stories you hear about that almost never happens. That being said I'm one of those unicorn stories but then again I had a hell of a lot of unofficial experience backing me up. I've run system's in professional configurations since I was little. I caught a break in my 30s and transitioned internally from a assistant position to their IT System Administrator after their IT Contractor disappeared without notice with a pending SAM audit and left them holding a bag with a lot of over-provisioned licensing.

The accepted path is you get in via Help Desk Support. Several years as a T2/T3 may develop into additional responsibilities which overlap some with what a classical Sysadmin does which allows you to make the leap.

Certifications are a poor replacement for a degree. They show you are up to date sure, if you can pass them. Most of the time passing them is not about knowing the knowledge but about effectively dealing with issues that in any other business sector would be considered fraud and unfair and deceptive business practices, but they get away with it because it is wrapped up behind arbitration and non-disclosure.

Its done this way for profit motive and because you have no alternatives since only one place does the testing for these. Those can also be revoked for any number of reasons unrelated to the test itself.

In my opinion they are marketed fraudulently to employers as minimum qualification for a role while setting a very high bar; and inherently limit the number of people who receive them in a way where knowledge is only secondary to profit motive (repeat customers).

I've taught email server administration and had people I taught pass; and then when I tested with almost a decade of experience in that area, it was failed for issues not related to knowing the material that were outside my control. 1 month before they would even respond, 3 months of back and forth before they finally issued a full refund for the clear failures on their part and my pigheadedness about documenting every single conversation in writing (proper case-building). Unfortunately I can never share the specific details that are covered by the NDA so long as it is in place.

The parties involved also apparently have blanket liability protection which they received from some of their government contracts according to one of several lawyers I spoke with from my state's BAR referral line, when I was considering suing them. None would take the case without a significant retainer, and didn't have high hopes for a positive outcome.

HR also favors degrees.

If you have neither, many companies use this as a negotiation tactic to draw you in; and then low-ball you. You can have 10 years of directly applicable experience doing the same job and they will say "Since you don't have a degree or certification you aren't qualified, and we can't pay you what we would pay someone who is qualified; or We don't have that position available but we have another at .... whichver it is its <half pay or minimum wage doing the same skilled labor>. This is all done after you've invested time into the interview process for a position that clearly was never available to you, except they wasted your time so you would accept the low-ball as desperate people often do.

I still regularly see this happen with increasing frequency and stale certifications such as deprecated certs which you did pass; are the same as no certification. I keep a list of entities in my area that I will never apply to because they have shown they are bad actors. Incidentally, state run job board listings often have less of these because the companies involved have to certify the accuracy and availability of the jobs; often under penalty of perjury. Something to be aware of.

As for the most important skills you needed to do the job... Stress Management, Documentation, Risk Management, and Communication, followed shortly thereafter by a mindset of constant improvement.

If you lacked any of those; bad things happen.

Its not enough to write things down, you need to write them down in a way that at a glance you and anyone else get all the most important information tailored towards the job that will be working with it.

If you can't handle stress, you'll get high blood pressure, early onset diabetes, and potentially other medical conditions that will shorten your life. Nothing is worth your health.

Everything must go through a risk management paradigm. Before you run a command, you know it won't bring everything down, and have a contingency in place for if it does so you don't have to think. Its written, you follow each step mindlessly. You do everything you can to minimize risk to the business.

Communication, if you can't communicate in a professional tone and manner you will be crucified by holier than thou management. This includes non-verbal communication such as attire. They will walk all over you making your life hell, undercutting your authority; minimizing your advice, etc.

You know what you are talking about, but if you cannot communicate it along with the appropriate risks; you can't do this job.

You can find the bulk of most of the methodology you will need in two book volumes by Limoncelli Hogan and Chalup. TPOSNA.