It is not realistic to expect every game developer to invest a lot of money into security. It's like asking every apartment building to run its own fire department.
The responsibility of securing a platform should not fall on application developers anyway.
Yes it is, and liability across the industry is already late.
By the way, in some countries apartment buildings need several licenses, including one from fire department, before been allowed to have people living on them.
Microsoft could easily secure windows by blocking all rootkits/"kernel anti cheat". At this point that's probably the best option.
Games should never have kernel level access.
It’s not the nurses job to perform surgery either, that’s why they don’t.
The problem is that general purpose computing platforms are not supposed to be secured against the user. That's a WONTFIX.