All can be remedied by tweaking the algorithms and that happens all the time, you can also use a certain vertical directly for certain type queries (scholar search etc).
The same way that what a user might enjoy can be inferred the inverse of that can be used as a signal in the algorithm as well. Personalization is just relevance and all is just a matter of tuning.
I agree, it can be remedied by better algorithms - such that can recognize when I'm doing a search for a known item and when I'm performing exploratory search. In the first case, personalize away, in the second case, please show me everything.
The challenge is that people switch very quickly between these search modes and don't even think about it.
The same way that what a user might enjoy can be inferred the inverse of that can be used as a signal in the algorithm as well. Personalization is just relevance and all is just a matter of tuning.