Old laptops are great for things that the RPi gets attention for. With a bit of hunting, you can get them dirt cheap, and the integrated monitor is a huge bonus.
The one thing I really miss using x86 boxes rather than Raspberries Pi is the dd-to-sdcard-and-boot workflow. Makes recovery easy, trivial to back up the exact software you’re running on one. If the whole thing goes up in a fire, buy another identical Pi, write a new sdcard, and you’re back in business.
But yeah, otherwise if you’re not using the io features you get a lot more bang-for-the-buck buying used low-end x86 gear.
But yeah, otherwise if you’re not using the io features you get a lot more bang-for-the-buck buying used low-end x86 gear.