Likely because the parent said "Most of the population are wired for fibre" which is wildly misleading. FTTC would not fit most people's definition of being "wired for fibre".
Describing 80Mbps for FTTC as realistic is also a bit of a stretch. If you live in an area with modern phone lines and happen to be close to the local cabinet, this may be your experience but isn't that representative of the population as a whole. Per https://labs.thinkbroadband.com/local/ the mean download speed for FTTC is only 34Mbps, which given that some users are getting speeds of 80Mbps should tell you a lot about how poorly it performs for others.
I live in a very old village, some miles outside the nearest big city, and we routinely see those actual speeds on OpenReach FTTC. I suspect that the lower average figures have more to do with ISPs offering lower prices for a 40Mbps capped service (which does seem to have been quite common as FTTC has spread) and with some ISPs using much higher contention levels than others.
In any case, even if 34Mbps is the real world average download speed for the type of fibre connection most homes would be using today, that's still much higher than the figures in the article would have suggested for a typical UK home Internet connection speed.
34Mbps mean, across a population of ~67 million, suggests that there are substantial amounts of people getting much less than that. The data is broken down in more detail here[0], and while this isn't limited to just FTTC connections it still has some useful data.
Some takeaway points: Firstly, median speed is always lower than mean, often significantly so, as the mean speed is inflated by users with very fast connections. Secondly, the bottom 20% get very poor speeds, often in the ranges mentioned by the article. Perhaps the article should have said 20% rather than 40%, but I'm not sure that really changes the sting of the title much? Thirdly, and I think this is in some ways the most important takeaway, some users getting excellent connections appears to have no correlation whatsoever with users overall in that area. For example in the City of London, a very wealthy area generally, the top 20% get 94Mbps and the mean user gets 56Mbps. Howwever the median user only gets 39Mbps, and the bottom 20% get only 6.5Mbps - which is definitely little enough to experience the problems in the article.
And for the record, I too live in a very old village, some miles outside the nearest big city, and I pay for the best connection possible to get, which gets me actual speeds far below the "minimum advertised speed" it's supposed to reach. The problem is down to aging aluminium phone lines, which Openreach refuses to replace.
Describing 80Mbps for FTTC as realistic is also a bit of a stretch. If you live in an area with modern phone lines and happen to be close to the local cabinet, this may be your experience but isn't that representative of the population as a whole. Per https://labs.thinkbroadband.com/local/ the mean download speed for FTTC is only 34Mbps, which given that some users are getting speeds of 80Mbps should tell you a lot about how poorly it performs for others.