This was a hugely significant change in the climbing community at the time. There was real risk involved in climbing "clean" without pitons. A piton hammered into a granite crack is very solid protection, it's pretty straightforward to find where to place one and to place one in a manner such that it will hold a fall. In contrast, it takes a lot more skill and experience (neither of which existed anywhere initially) to place a hex or a nut correctly. And if you place them incorrectly, or even if you sling them incorrectly, there's a very real risk they can pull out or not hold a fall. Moreover, passive protection of this sort only works in certain kinds of rock, some of the more popular routes at the time were cracks which were very hard to protect.

This meant that a lot of very popular routes became a lot more dangerous to climb cleanly. To their credit, the climbing community just accepted that and moved on.

It wasn't until the late 70s that cams (SLCDs) were invented and clean protection devices attained sufficient breadth to protect very nearly any climb that could have been protected with pitons.