On the first part, that's true, but you don't have to actually care about those further career steps. Tenure you have to care about, because you're out of a job if you don't get it. But a tenured professor in CS has a permanent position with a good salary, regardless of whether they ever get another promotion or not. Some people do really care about the Full Professor title, but it's not mandatory that you take those further career steps particularly seriously.

A bigger issue post-tenure is the money side of things. Do you need significant funding to carry out the kind of research you want to do, e.g. because it needs reasonably expensive equipment or employee/minion labor? If yes, you do have to care what people with money think, whether it's funding agencies or corporate donors, and that constrains the research you can do. If no, e.g. because you work on your own projects and don't particularly need equipment or a large lab of minions (common in areas like theory and logic), then you don't really have to care about the funding agencies, either.