Mini PCs are super cheap and powerful now. Old laptops are more likely to die, technology has a lifespan.
Discussion
I also like mini pcs but old laptops are cool, have a screen can failover briefly to battery and are usually way over powered.
We easier to just use the desktop with screen though for setup for a normie.
Then of course have options for backing up
Mini PC that I bought 4 months ago nearly doubled in price.. I shoulda got 2 of em..