Technically legal since Steam grants ownership?
They explicitly do not.
> The Content and Services are licensed, not sold. Your license confers no title or ownership in the Content and Services.
https://store.steampowered.com/subscriber_agreement
They explicitly do not.
> The Content and Services are licensed, not sold. Your license confers no title or ownership in the Content and Services.
https://store.steampowered.com/subscriber_agreement