In the world we are in today many find it very hard to trust new crypto projects and team going anonymous is even more worse, people will have less trust on such project, even if the project use case is very good it's a wise decision for the team to come out in the open
If you trust the technology that they bring up could be success in the future I think it does not matter to involved/jump in anonymous team project. But the thing is we couldn't find such kind of project these days and beside most of them are anonymous, the project itself does not has any real usecases or new solutions to the current market.
That's not easy to trust even if their technology is trusted. There is no guaranteed that it will succeed, and if the team is completely anonymous, I don't think that it is good to join with that kind of project. But yes, we couldn't find any project such that and most of the anonymous team or even if the identity of the team is in public, the project being legit still depends in their intention.