I'm the author of the post. Yeah you got it right, I think the hiring process got me into that mindset, i.e. "This is a step back from you title-wise but you'll get back there quickly". So the hiring process made all that look too easy and in retrospect got me into the wrong state of mind.

What I should have done, at the point of being hired, is to drop all that, and focus patiently on what I needed to do. And I'm sharing it because not enough people share this side of it, and because I am working on elements that would have made it better. Thanks for reading! :)