From the advertisers perspective; they may not want to spend ad dollars on people who are already highly likely to use their product or service. Ideally ad spends have you picking up customers on the margins that you otherwise would not have and this is very likely to play into targeting decisions.
The thing is, I'm actually interested in soliciting suppliers for various things. It would help me out quite a bit if they came to me rather than me to them. I make cheese. I need cheese making supplies. I travel from Japan to Europe once a year I need flight tickets. I'd love to upgrade to slightly bigger seats if I can afford it. Show me some comparison prices against your competition in that area. My bank is driving me crazy but it's the only one I can find that handles forex without charging me an arm and a leg. If you're good on that front, try to upsell me on something else. I'm interested in wet shaving and I need a supplier for products. I need a credit card, but I can't get one normally because I'm not a permanent resident in Japan. I know there are solutions, but I'm not aware of where to look. Various dry food staples are hard to get in the grocery store in the rural area where I live. I could give you a list if it would help. I am likely to travel somewhere in Japan 2-3 times this year for the purpose of visiting an onsen and staying over night in a Japanese style inn. I go to Saitama about 6 times a year to watch baseball and I often want to stay overnight. I'm not sure if it makes sense to stay in a hotel or AirBnB or something else. I need to buy tickets to Disney Sea this summer and I'd like to do it ahead of time if possible.
Seriously, I could (and would) go on for a long time. I have tons of things I'm likely to buy for which I'd love some help. There is a lot of personal information in the above, but all of it is stuff I'm happy for the world to know. There is a lot of other stuff I don't actually want to advertise and I'd rather the two categories didn't get mixed up.
The easiest is to sell more to people who are already your customers. That's the main target. Occasionally you also want to try to conquer new people, perhaps from your competitors. Those are the two targets, out of which the first one is more important.
