I fully agree with this.
Not only should you not focus on product, but when clients bring up product you should of course listen carefully and respectfully, but you need to consider that they are even then expressing ideas about how to solve their problems. Those ideas may be well thought through, but very often they are not, and comes down to trying to explain what they need based on what they know.
If a client says "we need product X", sometimes they really need it, but often what they are trying to communicate is "we need the stuff product X's marketing material says it will solve", and even that may be imprecise
Someone coming in quoting on what they say rather than what they answer when you ask probing questions about their actual problems will often quote for the wrong thing. And more importantly: Quote for something that someone else will be explaining to them why is the wrong thing while quoting for something more appropriate. Doesn't help if you come in with the best price if someone else has made your solution irrelevant.
The other aspect is that people often value the solution to a problem far higher than they value a product.
I have built a tool that I'm starting to roll out a service around now. And the interesting thing is that when I've talked to people about it, it quickly became clear that if I showed them screenshots of my admin interface and explained the software, they started comparing it to $20/month services that in fact deliver far less value in terms of results, but they still found it hard to see it as something more expensive.
When I instead approach it entirely in the abstract, and show people analytics of the outcomes and never tell them I have a pretty web-based interface, and never suggest they'll get a login to anything, people consistently value the service 10x to 20x higher.
Now, this doesn't work for everything - the reason people value it so high in the latter case is that the analytics makes it clear it deliver results that would cost them in that region otherwise. But the moment I start to describe it as a product, people go blind to the outcomes and value it based on other criteria.
tptacek and patio11 have touched on this previously too when talking about how to get your rates up by focusing on value delivered, and avoiding billing in small increments (e.g. bill daily rather than hourly, or even bill by the week or by the project if you can). But beyond applying just to the price, the overall principle also greatly affect whether or not you'll get a deal at any price.
Someone may even suggest the exact same technical solution as you, cheaper, but still lose out if they focus on the product and you're selling problem solutions and visions of where it will get them next.
E.g. I had a client meeting yesterday to walk through a proposal I'd sent, and the entire meeting involved me telling them what problem each part would solve and what that'd enable next. They sat there grinning through most of it, and kept starting to discuss additional work they just thought of that this would enable them to do later, and cost came up just very briefly at the end. Never mind the initial contract - selling them on the idea and the problem solutions now rather than technical details of a specific product likely already did 90% of the job of selling in 3x+ more work down the line.