Even static websites can have comments to their blog pages. But require some external services.
Comments for static websites
Many blog sites let visitors to leave comments thant can be viewed at the bottom of page.
This can be done even in static websites but require a service which deliver a dynamic content.
Some of them are free with premium services for sale, some others uses some trick to interface with external services, and some are self hosted.
The most famous service is Discus which has a basic plan supported by AD and premium service ad-free
Particular is Gitalk which let you to add comments using github commenting system. A similar approach is used by staticman
Someone are totally self hosted and open source one is isso but since they are self hosted sometimes they are a little bit harder to implement.
A little internet searching let you to find many many more solutions.