They are cheap and durable, and they work with most major Linux distros without much headache.
I have a spec’d out S76 Lemur, which is a great laptop for throwing in a backpack as a daily driver, and really packs a punch with a small footprint.
But I also have a couple ThinkPads that cost less than $100 to replace that I use for doing experiments in the field where a laptop is more likely to get damaged. No need to needlessly drag thousands of extra dollars in kit out into a mountain trail to do radio experiments. For that kind of work, these old systems have more than enough resources, and if I fall in a stream, or get caught in rain, the worst I have to do is replace the system for $80 refurbished on Amazon.
Of course, I’ve never actually had any issues requiring replacement, but ThinkPads are really hard to break. I’m not as convinced about the Lemur’s durability, and would rather take fewer risks with it.