That 10% in the article is people with long COVID, which is not necessarily debilitating. Just having a reduced sense of smell is a symptom of long COVID, but it's not going to stop a runner from running. I tried looking for statistics and I found that in a USA survey, 26% of people with long COVID, reported significant activity limitations. https://www.cdc.gov/mmwr/volumes/72/wr/mm7232a3.htm

It's also all uncharted territory: traditional tests can't identify long covid and there are still breakthroughs being made to figure out what is actually going on with long COVID. It'll be some time before it can actually be tested at scale and even if it can be tested, I doubt that this will be done. As the article suggests, it'll probably be more convenient to try and sweep it under the rug, definitely cheaper.

For now all these statistics are based on external symptoms: people who were diagnosed with COVID (not everyone who had it, was diagnosed), who found that they had long lasting effects (before ending up in statistics, it had to be bad enough for them to seek help) of whom a part has very noticable negative effects (people who did not do much physical activities before, might not even be aware that they can no longer do the physical activities that they didn't used to do), ... So it's error on top of error, a whole lot of unknowns. The percentages in the doomsday article could be accurate, but without the ability of testing, we're not going to find out for a bit longer.

That you personally don't know anyone who has long COVID, does not surprise me. It's such a vague disease that it's not a good talking subject, people just carry on as good as they can. Personally I only communicated my struggle with it to people who were affected by my change in behaviour: I cancelled walking trips and I wanted people to know that it was me, not them. And my garden was a shithole, which was also a me issue.