I have another possible explanation that I cannot corraborate with online sources at this time.
I visited Japan several years ago, and as one does (and should definitely do), I visited many Buddhist temples and Shinto shrines while there. I believe it was a Buddhist temple (as opposed to a shrine) where I first noticed two sets of stairs. There was a steeper set, much like the ones pictured in the question above - not unusually steep, that led up the hill/mountainside and through the main gate of the temple.
Chion-in (知恩院), Kyoto main stairs:
Then there was also a much shallower set, with the flat part of each stair being slanted and perhaps as deep as six feet/2 meters, and the riser of each step being less than four inches/10 centimeters. These gentle, shallow "stairs" (more like stepped ramps) were hidden from the main view of the temple, and came up the back or side of the mountain to a plain entrance.
Chion-in (知恩院) "back" stairs:
I asked the walking tour guide why there were two sets of stairs, and I expected it had something to do with moving large statues or other mechanical tasks and services. According to the guide, however, it was actually meant to segregate the men from the women, to the disadvantage of the women.
At the time the temple (and many other temples besides this one) was built (according to the guide), women were required to wear clothing that greatly restricted their movement. They could only take short, shuffling steps because of the tightness of the wraps around their legs. That meant they could not climb a typical set of stairs. I'm not sure which fact led to the other, but the synergy was that women could not mount the main stairs and enter the main entrance to the temple along with the men. They had to shuffle up the back stairs which were carefully designed to be just climbable by women in the required clothing.
I have no knowledge of prohibitions on women climbing mountains to shrines or temples in China, nor am I aware of similar clothing restrictions. I only mention this because there are some cultural similarities between Japan and China, and when I saw the pictures of the steep stairs and the gentle switchbacks, it occured to me the stairs could have been made difficult intentionally.
A less sexist possibility is that since the stairs are likely leading to some place that has some sort of religious significance, the climbing of the stairs represents a sort of pilgrimage or penance, and therefore should not be made too easy on the penitent.