Smart people should think about doing stupid stuff, not necessarily follow through and do it. Selling TV wall mounts online is not a very great contribution to human progress from someone who was experimenting with ferromagnetic fluids. This is advice on how to stay alive and make a living, not advice on how to achieve your full potential and help humanity.
You speak like a person who has never had a grant proposal turned down. Congratulations! May you continue to enjoy your life in the ivory tower until retirement.
However, for better understanding of how other people's lives work you may want to google Maslow's hierarchy of needs, where you will encounter the observation that a person who doesn't have a secure source of food and shelter often has a lot of trouble caring about their contribution to "human progress".
A lot of people will hand you money in exchange for TV wall mounts. There are a lot fewer people who will hand you money in exchange for research data on ferrofluids, and there are a lot of people in line for that money.
And plenty of "stupid" things do mankind some good. Amazon invested a whole lot in selling books online, and now they contribute significantly to our quality of life.
That said, I acknowledge in the article that there should always be those aiming higher.
It doesn't seem like it is, but it may very well be a great contribution. If you make it easier for many people to find something, what do they do with the aggregate free time they now have on their hands? If you make it cheaper, what do they do with the aggregate 'unused' money? If the time and money enables yet another 'simple' contribution to freeing up time and money, then how far does this snowball roll? Perhaps it will end up freeing us to do humanitarian work, because there is really nothing else that requires our time and money?
It's a similar question to: "What most reduces human suffering? If Eliezer keeps doing what he is doing or if he goes to Africa and helps people survive in a refugee camp?" It may turn out you are wrong about everything and helping in a camp would have been better for humanity. Hindsight is 20/20 here and the scale of effects does not allow one to properly estimate them.
Philip Greenspun says this very succinctly in his article about why there aren't women in science.