> Creating POPs is not as trivial as creating a Heroku or Render like service on top of public clouds.

I didn't claim that it was.

> Unless the CDN has a good edge-close-to-cities presence and a high number of those, users will generally not see value in the CDN.

A home truth is that most CDN users don't give a monkeys about per-city POPs. If you just had one POP per continent that would probably be sufficient to cut latency by ~75% for cache hits. Many real world CDNs have <50 POPs (eg CDN77, which has 33) and some have <25 (eg BunnyCDN sells a package with just 8 POPs). These businesses have already existed for some years and have a real customer bases.