I've been doing this job for almost as long as they have. I work with companies that do on-prem, and I work with companies in the cloud, and both. Here's the low down:

1. The cost of the server is not the cost of on-prem. There are so many different kinds of costs that aren't just monetary. ("we have to do more ourselves, including planning, choosing, buying, installing, etc,") Those are tasks that require expertise (which 99% of "engineers" do not possess at more than a junior level), and time, and staff, and correct execution. They are much more expensive than you will ever imagine. Doing any of them wrong will causes issues that will eventually cost you business (customers fleeing, avoiding). That's much worse than a line-item cost.

2. You have to develop relationships for good on-prem. In order to get good service in your rack (assuming you don't hire your own cage monkey), in order to get good repair people for your hardware service accounts, in order to ensure when you order a server that it'll actually arrive, in order to ensure the DC won't fuck up the power or cooling or network, etc. This is not something you can just read reviews on. You have to actually physically and over time develop these relationships, or you will suffer.

3. What kind of load you have and how you maintain your gear is what makes a difference between being able to use one server for 10 years, and needing to buy 1 server every year. For some use cases it makes sense, for some it really doesn't.

4. Look at all the complex details mentioned in this article. These people go deep, building loads of technical expertise at the OS level, hardware level, and DC level. It takes a long time to build that expertise, and you usually cannot just hire for it, because it's generally hard to find. This company is very unique (hell, their stack is based on Perl). Your company won't be that unique, and you won't have their expertise.

5. If you hire someone who actually knows the cloud really well, and they build out your cloud env based on published well-architected standards, you gain not only the benefits of rock-solid hardware management, but benefits in security, reliability, software updates, automation, and tons of unique features like added replication, consistency, availability. You get a lot more for your money than just "managed hardware", things that you literally could never do yourself without 100 million dollars and five years, but you only pay a few bucks for it. The value in the cloud is insane.

6. Everyone does cloud costs wrong the first time. If you hire somebody who does have cloud expertise (who hopefully did the well-architected buildout above), they can save you 75% off your bill, by default, with nothing more complex than checking a box and paying some money up front (the same way you would for your on-prem server fleet). Or they can use spot instances, or serverless. If you choose software developers who care about efficiency, they too can help you save money by not needing to over-allocate resources, and right-sizing existing ones. (Remember: you'd be doing this cost and resource optimization already with on-prem to make sure you don't waste those servers you bought, and that you know how many to buy and when)

7. The major takeaway at the end of the article is "when you have the experience and the knowledge". If you don't, then attempting on-prem can end calamitously. I have seen it several times. In fact, just one week ago, a business I work for had three days of downtime, due to hardware failing, and not being able to recover it, their backup hardware failing, and there being no way to get new gear in quickly. Another business I worked for literally hired and fired four separate teams to build an on-prem OpenStack cluster, and it was the most unstable, terrible computing platform I've used, that constantly caused service outages for a large-scale distributed system.

If you're not 100% positive you have the expertise, just don't do it.