Is School of Thought related to the Rationality Community?

Never heard about them.

(Well, it's not like the Less Wrong community has a monopoly on talking about biases. Topics like rationality, critical thinking, intelligence, logic, etc. were popular long before LW existed.)

If you scroll down on their company page, you can find names:

Jesse Richardson - an internationally award-winning creative director and founded the School of Thought in order to popularize critical thinking by combining design with philosophy. 

David Lenowitz - after studying at Wharton and working as a Chief Information Officer at Susquehanna International Group, Dave was the founding Executive Director of the Alliance for Decision Education, and has over 30 years experience inthe technology and research sector.

David McRaney- a science journalist, author of several best-selling books including ‘How Minds Change’, and is the host of the popular blog and podcast at youarenotsosmart.com which explores the many ways in which we suffer cognitive biases.

Barry Silverberg - has over 45 years of nonprofit professional and volunteer leadership, management, resource development, and communications experience focusing on nonprofit governance, strategic thinking, board engagement, professional and organizational development, and public policy awareness and advocacy.

...at least, that's what they say about themselves.

I am impressed by their marketing skills, but I doubt the usefulness of the material.

For example, clicking on "the dunning-kruger effect" tells me that experts are often under-confident and idiots are often over-confident. That's true, but... not really useful.

It feels like the only purpose of that section is to make me buy their book on Amazon, and to conveniently share the link on social networks (perhaps when I want to accuse my opponents of being over-confident idiots). It's hard to say whether stuff like this actually helps or hurts people.

(From my perspective, an important part that is missing in that very short description, is that when experts become familiar with the opinions of everyone else including the idiots, their self-confidence usually increases. But when idiots become familiar with the opinions of everyone else including the experts, their self-confidence remains the same.)