Entirely true in some ways, but it may not matter as much as you think.
Seeing very large numbers of cases has a tendency to change political and ideological views over times. The appointees they get are vetted in various ways to at least be qualified at the law, even if they have strong ideologies.
Now, certainly, "true believers" aren't going to change, but ...
Plus, the federal judiciary doesn't pay well (relatively speaking), so unless they strongly care about deciding hundreds of random crappy cases, they often leave for greener pastures.
Seeing very large numbers of cases has a tendency to change political and ideological views over times. The appointees they get are vetted in various ways to at least be qualified at the law, even if they have strong ideologies. Now, certainly, "true believers" aren't going to change, but ...
Plus, the federal judiciary doesn't pay well (relatively speaking), so unless they strongly care about deciding hundreds of random crappy cases, they often leave for greener pastures.