I have wondered too. Many have come in past and disappeared. But some are still quite stable. I see many influx of projects Who look like they are just coming around to get investors money. Many of them don't really have viable use cases. That been said, the market has lots of potentials to provide solutions to certain problems that traditional market has tried to solve. For now, many projects are still trying to find their standings. They are still at their infant stage. There might not be need for more altcoins for now.