You quote 'we can help you track down and troubleshoot WordPress issues.' - that's exactly what the support team helps customers with all day long.
But we don't get into consultancy around helping to build custom code, etc.
There's always going to be a point where a hosting provider will not be able to support you further. Many dedicated providers and VPS providers will ensure that the machine is powered up and has connectivity and leave you at that. What we're trying to communicate is we go a lot further into supporting your use and configuration of WordPress - but not into consultancy.
I know Jacques didn't mention that the problem was with the stock installed-with-Wordpress Recent Comments widget until a couple of hour after you posted that comment, but _surely_ someone at WPEngine knew already that this wasn't a "custom code" issue?
From what I'm reading (and please correct me if this is wrong) a stock WP install with no plugins or custom themes, but with several hundred thousand rows in the comments table and the Recent Comments widget running - will crash hard on WPEngine (while running just fine on a "loltastically over provisioned Linode VPS).
In my view - that's a "Wordpress support issue" suitible for diagnosis by a "Wordpress expert", and a long way from "consultancy" for "building custom code".
It's true there needs to be a limit to what customers expect from hosting companies, but like it or not, you've set the expectation bar _very_ high with the marketing copy on your homepage, and you've got a wonderful social media reputation based on those expectations. At some stage, you need to suck it up and dedicate the time/expense to live up to that reputation, or inevitably social media will bring your reputation back down in line with your business behaviour/policies - and the wider the gap between the expectations you've set and the service you deliver, the more ammunition you're handing over to "the haters" to shoot you with.