Dublin is by no means a 'backwater' - Google and Facebook's EU headquarters both sit in Dublin, as well as large outposts of a number of global financial institutions. There's a lot going on in Dublin, not to speak of its history, accessibility, and affordability compared to the canonical 'tech hubs'.

Let's not forget that there are many engineers who don't live in the Bay Area, NYC or London, for whom Dublin may be quite attractive. And while it may not be on the level of those three regions, it has a lot going for it in its' own right.