There's two types of advertising (probably really more):
1) We don't care where you buy the thing we make, just buy it. (Mazda)
2) You want that thing in #1, come buy that thing from me! (Mazda dealership)
I don't think there's ever been a question of the efficacy of #1, but #2 is probably nearly useless online. Anecdotally, an advertisement might remind me I want something, but it isn't going to change my habits in how/where I buy it. Bob's House of Laptop Batteries could offer me a price that's $2 less than Amazon, but if I see Bob offering the exact battery I need at exactly the moment I need it, there's still a pretty good chance I'll buy it from Amazon because of 1) ease, 2) trust, 3) Prime, etc.
There's two types of advertising (probably really more): 1) We don't care where you buy the thing we make, just buy it. (Mazda) 2) You want that thing in #1, come buy that thing from me! (Mazda dealership)
I don't think there's ever been a question of the efficacy of #1, but #2 is probably nearly useless online. Anecdotally, an advertisement might remind me I want something, but it isn't going to change my habits in how/where I buy it. Bob's House of Laptop Batteries could offer me a price that's $2 less than Amazon, but if I see Bob offering the exact battery I need at exactly the moment I need it, there's still a pretty good chance I'll buy it from Amazon because of 1) ease, 2) trust, 3) Prime, etc.