Of course it didn't stop them playing Frontier - there wasn't anything else out there.
Right now, there's 2 candidates - Elite Dangerous & Star Citizen. Both actually different (Disclaimer: Backed both). Times have moved on, and for Frontier to deliver the experience they think is crucial to its' success, means that unfortunately offline is no longer an option.
If my lifestyle meant that this removed ED from games I could possibly play, I would be annoyed, but then move on. You won't be playing Star Citizen offline, either (and I am aware that that's not part of the discussion at hand, but thought I'd mention it).
The hard truth we have to understand is that online games are the way forward for multiplayer-online games. Note that I make a distinction there, that online is the way forward for Multiplayer games. As our hardware and networks improve, it'll become the norm and the entire idea of "offline" will be lost in the ether in a decade.
You forgot to add that squadren 42 is the offline single player mode of the game. Even star citizen is offering that.