This is just an ridiculously offensive stereotype. If you were in downtown Stockholm this weekend, you couldn't even tell there was a pandemic considering how many people there are one the streets.
Is it offensive? Well, maybe, but that's tact. However, is it true? Bear in mind that an excessively gregious society, and yes there are differences in societies, cultures, might view a more reserved culture as such.
And the real reason I'm responding is, how many "people there are on the streets" is irrelevant, in terms of being 'social' or not. People going places != social. It can equal work, needing supplies, traveling, etc.
I grew up in a small town, population < 1000, in a massively large county (>1000 square km), with barely 15,000 people in it at the time. When I first moved to the city, I would walk down the street and wave at people. People reacted, to my perspective, quite oddly. Some actually shied away, others looked at me as if was a lunatic.
Yet where I grew up, not waving would have been beyond rude. In the city, it was seen as absurd behaviour.
I guess what I'm saying is, Sweden could be quite anti-social, without it being "mean" to say so. It's all perspective.
I was not doing value judgment, but just an observation
As per my example, it is rude to not wave, stranger or not, at least where I grew up. Yet when I moved to the city, entirely different! Same language, country, region. Just urban vs rural.
So it is not surprising to see nation-wide cultural differences.
My non-swede co-workers had one thing in common theme while living in there: loneliness...
Swedes usually stay in one tight group of friends... and don't branch out as much as other societies do.
I get you have the FIKA culture and all, but it always within your few friends/group. And during winter, most people hole up most of the time due to the weather.
I am neither american, nor a neighbor of yours, and I am just giving you my experience. (lived there for few months).