It's relatively easy to dismiss advertisement provided you don't get bombarded with them frequently, at which point, it's simply learning via spaced repetition.

I get your point that a lot of knowledge acquisition that goes into short and long term memory has more to do with the environment (passive learning) and less to do with intentional learning.

Blocking the input entirely will always work (using headphones, not reading certain things).

I don't really agree. There are countless ads I have zero recollection of because I don't care in the slightest. I'm a guy, and I remember Playtex commercials for women, because it is interesting in a way what women deal with IMO. Now, you can argue that advertising works to make me interested in something enough to choose to care, but that's different.

Which is why I go out of my way to avoid advertisements as much as possible.