I read that CNBC article, and shook my head. Poorly written by a non-expert. Some primary reasons the big cloud companies design their own chips seem to be:
1. They have sufficient demand within their own company to justify the expense of the design teams and other development requirements (mask sets, etc). These companies can justify vertical integration.
2. TSMC has made using their foundry easy to use by creating a valuable ecosystem of hard and soft IP, development tools, etc. The richness of their environment is, frankly, a wonder in the semiconductor world. (Intel had better have one hell of an ecosystem strategy in mind.)
3. Custom designing chips, as Apple did with the M1 for example, can yield power and performance efficiencies beyond what merchant CPU, networking, and storage chip vendors can usually achieve while trying to please a broader market to maximize sales volumes. Flexibility for a merchant market usually has a price in some sort of inefficiency for any specific application.
4. Because the cloud computing companies have their own software ecosystem, Daniel's issue about software development has an easier solution when the chip design is in-house for these companies. Inclusion in the chip design process with top-down direction is the best possible scenario. Product-specific enhancements are more practical, like the inclusion of DRAM in-package in the M1. Will any merchant CPU vendor consider that? I'd bet against it. Not a big bet though...
5. Some fields of chip design, AI comes to mind quickly, certainly quantum computing too, do not yet have best known architectures that meet most needs. Where there's rich and diverse innovation there's more room for proprietary designs. Post-IEEE Ethernet networking appears to be another tempting field for the cloud vendors.
There are more reasons I think of, but I'm even boring myself.