It could be for reliability reasons as well, Something which was running for decades in a low-maintenance environment can be expected to continue doing so unlike modern semiconductors which are iterated and manufactured at very high volume that longevity is questionable.

I've been burned by semiconductors earlier due to bad design/manufacturing e.g. Pentium-D, SD 810 etc.

Also with current semiconductor shortage/supply chain issues/inflation, Anything to re-use (or) re-purpose old compute hardware is valuable to many.