You might think if they have not had symptoms why should it matter but it may matter if they then go on to infect vulnerable people who cannot survive even a mild infection.
If by vulnerable you mean those with existing conditions & the elderly, then most of them
can survive Covid, and do!
My Dad's nursing home is now in week 5 of the latest lockdown (the 4th this year), yet not one single resident has been unwell. They are all extremely lonely & depressed though.
Several haven't seen a single person without mask, gown & gloves for over 2-years. Its inhumane.
Dad has two competing 'high risk' illnesses & an almost permanent chest infection, yet he sailed through Covid in January - as have all the other residents. There hasn't been a single Covid-related death for over a year, despite the fact that all of them by definition are 'vulnerable'. The worst has been a couple of days of very mild flu-like symptoms (tiredness, aches & headaches), and then fine and testing negative by day 3 or 4. Despite this, they still have to fully isolate with their door closed 24/7 and minimal staff contact.
Few of us want to end our days in a care home, but I guarantee that none of us would want the sad & lonely existence we're still forcing on these residents 'for their own good'. There's a lovely park less than 2-minutes walk from Dad's home, but I'm not allowed to take him so he just lies in bed all day, staring at the same four walls (he's completely immobile).
Even at the very beginning there was a higher chance of a vulnerable person surviving Covid than dying from it - they were just at much greater risk than the young & healthy - and now, thanks to the vaccine, the overwhelming majority have a positive outcome.
That said, we've long accepted that thousands of flu deaths happen every year, so why not Covid? I suspect that in the long-term a high proportion of flu deaths will simply be replaced by Covid deaths, with the overall numbers staying broadly unchanged.
Staying away from others to avoid the risk of infection should be a personal choice now, not something we arbitrarily force on people. The same goes for testing.