Lockdowns were sold to the people as something that would stop the spread. If you can get every infected person to infect less than one other person on average, you can stop the spread of an infectious disease completely. At least in theory.
There are two variables here. How infectious the disease is and which percentage of the population can isolate themselves at home without society breaking down.
If everybody stays home you don't have hospitals, you don't have electricity, nobody picks up the garbage, and people will go hungry. Needless to say, that doesn't work. So what percentage of people still need to go to work? And it turns out you need a lot of people to work. From elderly care to daycare, from hospitals to supermarkets and their entire supply chain. And those people will inevitably get sick and infect their family and so the spread continues.
And how infectious is covid? Very, and variants increasingly so.
Which means you can use measures to slow down a disease like covid, but you have no chance of stopping it completely. And that's something some governments refused to accept, and they enacted a ton of erratic and ineffective countermeasures in a desperate attempt to do something impossible, instead of taking a more measured approach focused on slowing down the spread and increasing hospital capacity.
Some people will insist that government policy was in fact reasonable and measured, but it really wasn't. Deutsche Bahn still required masking in January. This year. 2023. I kid you not. It's totally absurd.