If it ain't broke don't fix it. Especially when the computers are relatively cheap compared to the bespoke hardware. My favourite example of this was the school district which used an Amiga to control the district's HVAC systems. Replacing parts occasionally on a 30 year old computer is far cheaper than an entirely new and unproved system.
But it is broken. This is not about rewriting a working server component in Rust just because or chasing the latest Javascript framework-du-jour.
What will it cost McLaren to renege on their maintenance obligations on those cars if one of these laptops are dropped or broken or stolen or just bite the dust (they are "getting less and less reliable"), and they can't source a working one?
Solid state doesn't mean that it won't wear out. Electron migration over time will eventually render ICs unreliable. To be fair, that's less of an issue at the process sizes of 90s semiconductors - but it still happens.
http://hackaday.com/2015/07/23/this-little-amiga-still-runs-...