Comparisons of quality are relative, Google was good from day one because it was better than the competitors at that moment of time. Problem is that if one starts using X, and that provides an edge, the other have to follow just to keep up. A very unfortunate rabbit hole.
I'm with you 100% that personal data makes search worse in in many cases, too much personalization is detrimental.
One last thing, which I'd like to stress, is that data from users is not necessarily the same as personal data. For instance, you can use the data from users as if they were just sensors, without trying to build sessions out of it.
In a way it's similar to what Google made when they started. Google was the first and only to use anchor text, which is user generated and a less noisier description of the content of the page. (True that they did not use the users themselves but they did the proper automatic crawling). But in a way they collected sensor data from users, not personal data. That's what we should still be doing today. The problem is , however, however, is that is too easy to go beyond "sensor data" and start to collect full sessions and even personal data.