No, the ELI5 is that the companies are posting jobs in a way that makes it very inconvenient to find online or apply for them, to ensure it goes to the H1B visa holder and not to an American national. (actually it's less about filling the job itself and more about the PERM greencard process, but that's not super relevant to the explanation.)

By law, these companies must prove the job cannot be filled by an American in order to hire the visa worker. One way to 'ensure' this is to only advertise jobs in newspapers or in radio advertisements, or in unlinked and unindexed webpages. That way, the American never knows the job exists, and the company can prove on paper to the Department of Labor that they tried to hire an American but couldn't find one. The InstaCart job posting for example requires resumes to mailed in through the postal service to their immigration department.

The goal of the project is to aggregate these jobs in a place that Americans can find and apply for them. An additional thing to note is that the company MUST respond to the US applicant within 30 days, or the applicant can file an official complaint with the government.