I'd say half of it comes down to Valve having the staff with the key knowledge and skills to provide support, and the other half comes down to not being public.
I'm sure many devs and publishers are filled with people who know that acts like this can garner trust and future support for their company, but will have efforts cut short because someone above complained that the line didn't immediately go up.
In every service or product I've bought, going public (and prep to go public) has preceeded a decline in quality. The day Valve goes public will be the day its downward trend starts, because its customers become the shareholders.
I'm sure many devs and publishers are filled with people who know that acts like this can garner trust and future support for their company, but will have efforts cut short because someone above complained that the line didn't immediately go up.