There are two statements by tobi that talk about izanagi.
1) During Tobi's anaylsis of Danzo's izanagi use.
He said the tech was even made forbidden by the uchiha. This statement implies the uchiha under there own power are able to the tech.
2) Tobi talking to Konan about Izanagi.
He said there have been others that boasted a imprefect izanagi due not to being able to control hasihrama's powers. This statement implies one needs hasihrama's dna to do the tech.
If you look at each statement alone one condricts the other. But if you look at the statements together you get a new understanding of the uchiha vs senju in their time.
The only way to make both statements correct;
There had to have been other uchiha in the past that tried to control hasihrama's dna to use iznagai and potenially izanami and in turn made the tech forbidden. This implies Hasihrama is aware of the tech as there have been other uchiha that tried to control his power and therefore Madara/tobi and danzo werent the only ones that tried this.