I’m not scared to pay serious money for a service, but putting your service behind a sales person is more than likely going to cost you my business.
It's what the sellers are looking for though. And the sellers generally are the ones making these sites.
If you want to put up a website describing what you want to buy, and put a very explicit chart about what you're willing to pay, you're more than free to do so.
Honestly, it seems to me that you just don't like the practice and so are rationalising.
In a market with a lot of sellers with essentially the same product (like a commodity market)? Sure. Prices tend to be pretty transparent in markets like that, because that's what buyers want.
In a market with a small number of sellers, with product distinction (different features, regulatory compliance, etc)? Depends on what we're talking about. Probably not on a thing like price, but a feature that a buyer is willing to pay for up front would probably be much more important.
A sales team closing on warms leads feels good and all, but you might be leaving cash on the table by running off people that aren’t interested in that type of sales cycle