Two issues, you can download and play your games in ‘perpetuity’ so long as Valve continues on the current operating model.

And Valve has not been particularly consumer friendly in the past.

They were found to be violating consumer rights in Australia at the very least and had to put a large notification on their storefront to disclose exactly what they had been wrong.

Valve were forced into providing a refund model and even then it often conflicts with consumer interest. Though admittedly bad actors will always try to abuse any refund model on digital products.