Because it was the only example of a developed nation whose health officials came out and said "given our circumstances, we think our country will be ok without anti-covid measures."
People who wanted (for a variety of reasons) to denounce anti-covid measures took those statements, stripped out the "given our circumstances" and said "see, Sweden thinks everyone will be ok without anti-covid measures."
The anti-covid groups, recognizing that nuance is doomed, did not respond by saying "Sweden might be ok, but we won't" and instead said "Sweden is wrong."
So why did people stop talking about it? Because the policy decisions have already been made. The political tool that is "Sweden says otherwise" isn't useful anymore.
Now obviously the academics and public policy experts have not stopped talking about Sweden (and the verdict is not even close to rendered), but since they are doing so out of the public eye it doesn't so much count.
So why should we have more public discussion about Sweden? It looks to me like this author believes it is evidence for the assertion "if the experts are struggling, the amateurs must be right." It is not. This kind of reasoning is virtually always the kind of justification someone comes up with when they need an explanation for why someone should trust a fringe conspiratorial theory of events over a mainstream expert-endorsed one.