Because what they want to do is ensure that the cards are not resold to miners, and instead stay in the hands of long term customers.
> You don't need to cripple the devices
First of all, they aren't crippled for the existing customers. They are only limited, for this other use case that the company doesn't care about.
And they do need to limit that functionality, if they want to prevent those cards from being resold to crypto miners.
> I don't support companies
Then don't purchase their product, if you don't like it. That is kind of the point of all of this. They don't want you as a customer. And it is their company, that they can do what they want with.
I don't support companies making the choice to limit their compute. I think companies should sell general purpose computers.