Yep, this is covered in the writeup. Results are accurate enough to gauge whether your post is doing well or not (keep in mind that this is a simple analytics system for a small blogging platform).

I also tested it in parallel with some other analytics platforms and it actually performed better due to the fact that adblockers are more prevalent than IP sharing per reader in this context.

It's a bad indicator especially since people who would otherwise not use VPN apparently started using this: https://support.apple.com/en-us/102602

Analytics doesnt need to be accurate. The important thing isnt really exact how many visitors etc. The important thing is trends. Do we have more users now than last week? Do we get more traffic from X than Y? If it is 1000 or 1034 isnt so important.

Not even mentioning CGNAT.