Games

They leveraged open source to compete on the console front without actually investing dev time.

This is just false.

Valve has funded a lot of extra work though to get things like DXVK and VKD3D-Proton for the translation from Direct3D to Vulkan into a state where performance can be really great! Valve also funds work on Linux graphics drivers, Linux kernel work and the list goes on.

reference

The included improvements to Wine have been designed and funded by Valve, in a joint development effort with CodeWeavers. Here are some examples of what we've been working on together since 2016:

• vkd3d, the Direct3D 12 implementation based on Vulkan
• The OpenVR and Steamworks native API bridges
• Many wined3d performance and functionality fixes for Direct3D 9 and Direct3D 11
• Overhauled fullscreen and gamepad support
• The "esync" patchset, for multi-threaded performance improvements

Modifications to Wine are submitted upstream if they're compatible with the goals and requirements of the larger Wine project; as a result, Wine users have been benefiting from parts of this work for over a year now. The rest is available as part of our source code repository for Proton and its modules.

In addition to that, we've been supporting the development of DXVK, the Direct3D 11 implementation based on Vulkan; the nature of this support includes:

• Employing the DXVK developer in our open-source graphics group since February 2018
• Providing direct support from our open-source graphics group to fix Mesa driver issues affecting DXVK, and provide prototype implementations of brand new Vulkan features to improve DXVK functionality
• Working with our partners over at Khronos, NVIDIA, Intel and AMD to coordinate Vulkan feature and driver support

from Valve's original Proton announcement

You should try doing some research before making such claims. Valve has been directly cooperating with, contributing to, and financially supporting several open source projects related to gaming since at least 2016.