I lose ownership of my laptop, you install whatever software you want on it (with the security risks that it conveys) and in turn "you let me connect to my computer"?
Or look at it another way: you wanted to buy/rent a server you intended to put in datacenter anyway. Now you can do the same with laptop.
Now on a serious note: internet can go down anywhere, even for them. There is nowhere stated that, if your old hardware misbehaves, you can use others, and there are privacy concerns with running your stuff on their software stack… So I don’t see a huge advantage honestly.