Certain idiots configure their store so that you cannot buy from them straight from the mall search screen. Instead, you have to actually go into their store and let hundreds of pages of crap load before you can start a purchase. KoLmafia not only lets you buy directly from such stores from the Purchases tab, but if you do a mall search in the relay browser, it helpfully provides purchase links for such stores on the search results. In other words, that "feature", used only by stupid shop owners, is a non-feature in the Relay Browser.
Now, that is a shop feature that not only does not help the buyer, but harms them. I am quite comfortable suppressing that.
Advertising budgets do not help the buyer - only the seller - but they don't harm the buyer. Therefore, I would say that KoLmafia "should not" ignore advertising intentionally - but I see no reason that we should complicate the code to do anything special to accommodate its existence. If you do a mall search in the Purchases frame, it displays the stores in the same order that KoL returns them, as lost says, and you get to make your own decision about whom to purchase from. Personally, I generally just highlight the first "n" stores and say "go buy x items" - which is to say, I am rewarding the advertisers. But then, the only things I buy from the purchase frame tend to be things that I collect, and I will buy out everything below a certain price, so it's moot; I will buy from your store if the price is right and will ignore you otherwise.
Now, using the "buy" command, you are automating purchases and one of our goals for automation is to go easy on the servers and minimize hits. If we can minimize price and also minimize server hits, then advertising be damned; as lost says, we reward those with larger stock, rather than advertising.
I see no problem with that. But then, I'm not generally sympathetic to "fairness" arguments about commerce - and I loathe advertising in real life, so why should I feel differently in a computer game? At least they haven't implemented a spam Kmail mechanism to allow store owners to fill my kmail box with messages touting their min-priced bat guano.