You're making a lot of assumptions there, and none of them are really valid.

First, good managers are busy people. Sometimes they'll be juggling a lot at once. My manager is also a team leader of a team with over thirty people. He has a general idea of how well everyone is doing, but by necessity that's not a lot in the way of details.

Second, marketing is as necessary a thing in the workplace as it is in sales. While I do wish I lived in a utopia where value-providers (whatever that means) naturally rose to the top and technically better products managed to sell themselves to the consumers, that's not the world. In the real world, those things just don't happen. So you have to market your company's products, and you have to market your own value. If I did not, I'm sure I could just go on existing in my current role pretty much forever, but that's not really my style.

A 1:1 isn't a drag or a necessary evil even if I remove the non-marketing aspects from it that I discussed in my post above. It's an opportunity to market yourself, where you have a captive audience for however long it's scheduled for. Captive audiences where you can sell are a pretty rare occurrence, so make the most of the opportunity!

Some people like to feel appreciated, so they'd talk up how well they're doing during the 1:1 each week and glow happily as their manager praises them for their good job - while yawning himself to sleep inside. Then the employee goes off feeling 'wanted' and motivated and everyone is happy.

Obviously this wouldn't be useful for everyone, but it's useful for some people. They're usually pretty easy to spot, too.