First, why are we looking at Google's N2 instances rather than N1 instances? The N1 instance would be $52 rather than $61, but the author hasn't talked about why they selected the more expensive N2 instances. Given that competitors don't talk about the CPUs they're using, it seems weird to select the more expensive CPUs for Google.
Second, Google offers dedicated hyper-threads. The author says that cloud providers (like Google) are more expensive, but they've compared dedicated hyper-threads on Google with shared hyper-threads on Digital Ocean. DO offers an 8GB 2 vCPU (2 dedicated hyper-thread) instance for $60/mo, but the author is using the 8GB instance with shared CPU for $40/mo.
So, with storage, Google costs about $52 while DO costs $60 for an equivalent instance. Linode's $60 8GB dedicated vCPU instance does come with 4 cores so it seems like a better value. One can also argue that the included transfer on Digital Ocean offers $8 in value. However, the premium for the instances alone isn't as big for Google. In fact, google seems cheaper.
Now, it's probably a fair comparison for Amazon's instance which only gives you CPU credits for around a third of the time.
Google's automatic sustained-use discounts and dedicated hyper-threads make it really competitive with Digital Ocean (if you don't need a lot of bandwidth) as long as you're doing an apples-to-apples comparison. DO's over-sold CPU instances will be cheaper because you're getting less. If DO didn't offer dedicated hyper-thread instances, maybe you could claim that they were equivalent. But DO literally sells something more equivalent for $60 rather than $40.
EDIT: Also, OVH is a bad comparison. OVH is cheap, but inconsistent in their product offerings. The author notes that they offer hosted DB services, but that's only in France. Their US, Canada, Singapore, Germany, Poland, and Australia locations don't offer that. Their US website is missing pricing on many of the things they seem to offer. Plus, at a certain point, when you're trusting someone with your datastore, you want a high level of certainty. OVH's website doesn't inspire confidence given how much seems like someone didn't even check it. It's certainly cheap, but it seems cheap for a reason.
One final thought: I'm surprised the author hasn't talked about transfer pricing. Cloud providers usually charge a bundle while others charge a lot less. 1 cent per GB at Digital Ocean is a lot less than the 9 cents per GB at AWS. AWS even charges 1 cent per GB for data transfer between AZs in the same region. If you're running a compute and Kafka cluster in 2 AZs, then writing 1GB to a quorum of 3 servers means paying 1.5 cents per GB written (assuming that half the time you're writing to 2 servers outside your AZ and half the time you're writing to one server outside your AZ). Likewise, when you go to read it, if half the time you're not reading from a local AZ, you're paying half-a-cent per GB to read the data. So processing 1GB costs 2 cents. That adds up fast. Everyone compares things like compute instances and seems to ignore data transfer costs. Frankly, Google is competitive on storage and compute costs with places like DO. However, if you are trying to create the next Imgur, you probably care more about transfer costs than compute or storage costs.