Yeah, that's a good way to put it, Anika: "one size fits all"!
And when someone holds a one size fits all view they do tend to come across as a bit ... well, obnoxious/arrogant/intolerant, take your pick(!) That goes for about every subject, imo. To each his own and all that.

Anika is totally right in saying that people can make great strides. (And knows of what she speaks.) Nothing comes without hard work, but WHAT that work entails varies from person to person. And sometimes even with hard work, success proves elusive. Anyway, if the book is obnoxious and making you feel bad, choose something else to read. If it's one of those "yeah, some of this might be useful but" things, you can set it aside. Some books are meant for another time. (And some are meant for no time at all, lol.)