It reads perfectly clear. It is designed to be a platform and mit license makes it too easy for other people to create competing services and they don’t want that.
Maybe it was a mistake on their part to make it initially open source or it is bad that there are people looking to steal other people’s work
If you don't want your work to be "stolen", and instead want to force the people to contribute back, use the AGPL
It's not possible to steal code, since the original author still has it.