It's a little more complicated than than just having to refrain from selling MongoDB services. There is a good page which summarizes the problem with SSPL. [1]
SSPL is crafted in a way that it very hard to tell whether you comply with the license or not, especially if you run it as part of a cloud hosted solution.
I mean, that's fundamentally what the website did. Claims without evidence can be dismissed without evidence. However, without any justification for the belief the author apparently has, the author asserts you cannot even expose MongoDB's API as part of your own application within the terms of SSPL, and that is neither in the letter nor spirit of the license terms, which solely relates to selling the software in question (MongoDB here) as a service offering principally as itself.
The author, of course, relies on the claimed vagueness of the license as an excuse to take every claim to the most ridiculous extent possible, even though no reasonable person would believe anything claimed here, such as the suggestion that it might entail you release the source code for your computer's BIOS.
In a section with truly atrocious spelling and grammar, the author asserts that somehow this kills real competitors (even though real competitors would presumably have their own actual product offering, not just re-ship a product offered by the SSPL software developer at a predatory pricing rate only made possible through monopolist behavior). They then make the ridiculous claim that this entirely removes the ability for the customer to choose their cloud provider. Meanwhile, in the land of reality, between either forks or licensing agreements, there is plenty of competition, but the developers have an opportunity to sustain development instead of all of the profit being skimmed off by Amazon, who contributes nothing back and does none of the work. Having to raise their prices above the original developers' due to license fees, of course, doesn't even remove the value add for choosing AWS, where the benefits are bringing it into the same datacenter and platform as the rest of your other cloud needs.
The author then tries to villainize software companies using SSPL by pointing out how many thousands of employees and how many millions in revenue they have, without acknowledging that the sole benefactor of making SSPL look bad is Amazon, which brings in hundreds of billions of dollars of revenue and has over 1.5 million employees.
This train wreck is then finished up with their suggestions that these companies should just remain unsustainable and rely entirely on business models for open source we all know don't work very well.
I would say the author is arguably wasting their $10 a year domain registration on this garbage article, but considering the lack of public attribution present, I assume Amazon's paying for it.
[1]: www.ssplisbad.com