Some (older) people have biases towards laptops (since their experience is limited mostly to older crappy laptops) and just suggesting that a laptop would be better than their current, ancient, desktop is met with refusal and denial.
I know this situation since my mother falls into this camp. When she last moved I tried to convince her to buy a laptop, but she refused. Later I got her Chromebook which she likes on travels, but still refused to use at home, but continuously complains how slow her desktop is.
I'm seriously considering if getting one of these for her would fix the situation. She could still use her old keyboard, mouse and display, but I bet performance would go through the roof (compared to her old PC), but I don't know how compatible things like printers and scanners are with this and would running mouse, keyboard, printer, scanner and external HDD off of same USB port introduce some bottlenecking