Is this a problem? This sounds like ordinary business development / product management. Let's say I started a cloud provider. A customer comes to me and says "we need something like BigQuery". The first thing I'd do is sign up for BigQuery and try it out, right?
If you're making an online marketplace, you probably want to try using other peoples' online marketplaces. Make sure you're not missing something obvious. Implement their good ideas, rework their bad ideas. That's competition.