Valve has been investing in Linux gaming for nearly a decade now (to my knowledge), and it's looking like a really good decision. I've recently set up new Windows and Mac devices and it's just glaringly obvious how tightly they're clamping down on their respective platforms. My perspective is a that of a Linux sysadmin who hadn't done a fresh Windows install in over a decade, and took about 3 years off of using Apple products.
It's definitely an arms race, and the experience is getting worse and worse for customers (including software developers). I don't know if the average user notices these things or not. Valve is trying to not get caught in the crossfire here, and to have some recourse when inevitably MS wants 30% to allow steam to run natively in Windows. In the meantime they also have built a strong reputation among nerds like us, mostly as a byproduct.
The grandparent is saying that Steam didn't want to have to run on Windows, so they're investing in Linux so they can use that as the base OS for gaming. Otherwise Microsoft could demand a cut.
I think you mean Steam Deck, Steam Link is a remote play box for your TV that was released in 2015 and discontinued (in hardware form) in 2018. Steam Deck is expected to release at the end of next month.
Steam Link is a bit more general than that - it also includes the mechanism that Steam uses to stream games to NVIDIA Shield, mobile phones, and between computers.
Steam has been releasing Linux based hardware and driving generic Linux support since 2015, if it hasn't been worthwhile for the last 7 years it seems an error to bet on the next new thing catching on this time before it's even released.
Even assuming Steam Deck (which is what I think you really meant) is an absolutely roaring constant success then they still realistically have a couple of years before it'd really be a significant chunk anyways. That's ignoring the whole premise of their other development, Proton, which is about running the Windows games on such systems anyways.
