I'm generally sympathetic to this stance, but the major drawback that has surfaced (when I've had this conversation in the past) is that discovery is a real thing that still needs to happen and ads can in fact help with that.
First in the obvious way: there are products that I have found useful that I would not have known existed if not for ads. The idea that you should only ever purchase something because you were specifically looking for it seems a bit silly, because that's not how it has played out in my life. Have I purchased stuff I didn't need, influenced by ads? Of course. But I've also purchased things which objectively made my life better, which I would not have even known existed without ads.
We are lucky to live at a point in time where most of the world's information is at our fingertips (via the internet) and we can quickly, easily, and freely find information about anything we could want. But this is ignoring the fact that a lot of this is in turn funded by ads.
e.g. when I'm trying to find something, I google it, which is free because their business model is ads. There are a lot of people who are reviewing products with high levels of trust on sites like YouTube (tech reviewers like MKBHD), but they are able to produce those videos (which I watch for free) because they too are funded by ads.
Sure, we could pay subscriptions for all those things, but as pointed out in the OP, that is a regressive funding model – it becomes harder for a poor person to find the best products if all the best product reviews are locked behind paywalls.