Hidden team should not the only one to look about the project. There are many project these days but you also have to search their white paper, their social media as what others said. There's no guarantee that the project will truly be sucessful in the end even they are hiding themselves. Actually, I don't trust such kind project that we don't know who runs it.
indeed there are many aspects that we must analyze before joining a project. A hidden team does not mean a scam, nor does it have a guarantee that it is legitimate. As you said, there is still a lot to be analyzed in more depth, for example, product usability, tokenomics, roadmaps, etc.
The increasing number of scammers, and the ecosystem full of risks, make investors more cautious and less trust in anonymous projects. Unless they can really provide evidence through a strong product and support from a trusted company.