Why put effort into removing them? They use a trivial amount of disk space.
It's not just commands that are actual for the current session (like ls/cd/cat), it's also incorrect commands or just commands not worth retaining still being saved among with the useful commands.
The most precious is user's time. And when you fzf part of the command with the regularly saved history and would like to re-execute something important - you'll first get a long list that you'll first have to filter to find the command you were seeking.
So to counter your question with another: why store garbage?
Also, when I do want to reference my deep history I often find that seeing the full list of what I was doing is helpful at getting myself back into the frame of mind I was in when I ran the commands originally, which can be more valuable than seeing exactly which commands I ran.
Then why write history at all? Just discard it.
Maybe 3 in every 1k of my command lines is noise. Finding anything useful in there takes effort, so I rarely use anything older than a few days.