This isn't really true; scientists also praised Einstein for his deep mathematical intuition. His work on Brownian motion and general relativity was new and difficult mathematics (GR still is). GR is also startling for the mind-bending fundamental intuitions behind it. He asked mathematicians for help hammering out details, but 1) everyone does this and 2) mathematical rigor and abstraction wasn't nearly as well-established back then as it is now, and was difficult to grasp for many physicists and even mathematicians. For example it was several years before Minkowski established the connection between special relativity and the "shape" of spacetime, giving rigor to Einstein's intuition--but doing so is nowdays an easy exercise in undergraduate mathematics.
I copied the quote from [1] however credible you find that source. (Though they provide references to several books at the end of their article.)
Also, Darwin:
"At no time am I a quick thinker or writer: whatever I have done in science has solely been by long pondering, patience, and industry." [2]
On a personal note, I entirely relate to the slow thinker. Most smart peers of mine are fast thinkers and I'll usually lose to them on puzzles and tricky math problems when it is a matter of speed, but then I'll solve problems that these same people give up on and claim too difficult if I can sit in a quiet room with my fists on my head.
I have a suspicion that fast thinking involves a developed ability to filter out (quickly) what seem like dead end avenues -- so the fast thinker can hone in on the promising avenues and get to a local maxima solution faster. But for some problems -- especially ones that require very non-traditional paths to solutions -- this filter fails and prunes away avenues that actually lead to a solution to that "impossible" problem or global maxima solution.
I realized a long time ago the danger in pruning away the "obvious" dead ends, so I think my slow thinking comes from a refusal to categorize anything as a dead end until it is provably so -- because of a worry I'll prune away the solution. A bunch of avenues will present and I'll need to consciously sort through them. So my filter is slow and requires me to retreat to that quiet room to go sort through all the possibilities. But then I'll come up with gold.
I have a theory that I'll put out here... that slow and fast thinking are developed tendencies not innate qualities. In my experience most of the smart people I know are fast thinkers. Which makes sense if this is developed, because there's an ego reward involved -- especially in our educational systems -- for developing that way. And the only reward for slow thinking is solving a hard problem, but as a kid in school, where's the external reward in that? And how often is the opportunity for solving really hard problems given? Basically what I'm saying is that I'd like to see more slow thinkers in the world. (I'm not kidding.)
As a fast thinker, everything you say here makes sense to me, especially about quickly pruning dead ends. I admire my slow-thinker friends for not doing that, and I've always considered slowing my thinking to be a top career goal.
As for whether it's a developed vs innate quality, I don't remember ever thinking differently and being trained to think the way I do because of my environment. I would agree that in our system fast thinkers are rewarded more, but that doesn't mean that our system develops fast thinkers at the expense of slow thinkers, or that its any less innate. It just means that slow thinkers have more difficulty being recognized earlier (hence "late bloomer" or missing the "precocious" label.
