It's only a "dig" because you, and some others, have chosen to take it that way.
Maybe you haven't actually read OP's Original Post?
Where is the OP post stating: "what on earth is wrong with you stupid British people" ?
I would be surprised, and yes, disappointed if OP ended up calling the British people on this thread, and generally " stupid people".
From the updates OP has posted, she seems to have replied with good humour and I haven't found her to be antagonistic in her replies.
There was ONE poster, way back, who said that walking down British streets at night could be compared to walking past stores that had been 'borded' up ( sic) as opposed to walking past stores brightly lit and decorated. ( Not a direct quote) but that was the gist, and I almost called her on it ( not OP btw).
I found that to be a slight 'dig'.
The first pages of posts were good, people were telling OP why they, as British people, generally preferred to have most lights off, and curtains closed, but they were also quick to acknowledge that British homes often have comparatively poorer insulation in homes and windows, and higher costs of electricity than in Sweden.
Somehow from then on, a FEW people changed the tone of the post , rallied round the flag and became incensed about it all.
THAT is what led to the spiralling down of the thread.
If the 'answer' is a simple as you say, and OP could have worked it out by herself, I would say than in half the posts on MN, the posters could have worked things out by themselves, but then, what else would we all be doing in the last few days but posting continuously?
She started her thread with a genuine question ime.
Banter and chat are good, and disagreements can't be helped but please don't make this a bigger thing than it needs to be.
In the end, we all do what we're used to, and what we want to.