This is all true. But... But if you manage your own server, as the author advice, you need to figure out a lot of stuff and remember about a lot of stuff.
Are ulimits set correctly?
Shall I turn on syn cookies or turn them off because of performance?
What are the things I should know but I don't and Chat GPT has not told me them, as this is more than some intro tutorial on how to run VPS on DO, so it was never indexed by Chat GPT and alikes.
Is all of my software on the server up to date? Is there any library I use exploited, zero day attacks are on me too, blocking bots, etc. What if I do some update but it will turn out that my Postgres version is not working correctly anymore? This is all my problem.
What if I need to send emails? These days doing this ourselves is a dark art by itself (IP/domain address warming up, checking if my domain has not ended on some spam list, etc.).
What if I need to follow some regulations, like European Union GDPR compliance? Have I done everything what is needed to store personal data as GDPR requires? Is my DB password stored in a compliant way or I will face a fine up to 10% of my incomes.
This is not black/white situation as the author tries to present and those who use cloud services are not dumbards who are buying some IT version of snake oil.