We’ve run Lenovo (and formerly IBM) Thinkpads all day, every day, in a relatively warm environment for years without issues so I don’t think it’s fair to globally state that all laptops have poor thermal design.
My personal choice for running WD and scripts etc. is a low power desktop. I have three Intel Atom (fanless) mini-ITX PC’s running 24x7 for various purposes. But if I was buying a new one today it would be a mini box like the Intel NUC or less expensive brand.