That's not a super helpful reply.
(1) The article you link to seems to be a joke.
(2) You say '"free" gmail has no SLA or any other obligations to you, the user', but I've received much more valuable email service, without SLA, from gmail, than I've received, with SLA, from Dreamhost. SLA seems fairly useless in practice. Once Dreamhost credited my account with $10. Very kind of them but it didn't cover the loss I had suffered.
(3) Fortune-500 companies are obviously not relevant to this discussion. What is relevant, are organizations that would typically be customers (for webhosting) of Dreamhost. For example, small businesses with 1 to 5 employees, or clubs with 10 to 50 members. The question is, where should they get their email.