I've used SimpleX for seeral years. I do like the concept, and I have supported the project, but in my opinion it suffers from two weaknesses/lacks:
1. It cannot synchronize chats across several devices, so you need a separat “account” for each device. This can, to some extend, be mitigated by creating a group for each contact you communicate with, and then add all their and your accounts to that group.
2. Message propagation is somewhat unreliable: If you use the method described in (1), some accounts may not receive a given message.
But yes, you needn't disclose your phone number in order to create an account/profile on SimpleX.
1. It cannot synchronize chats across several devices, so you need a separat “account” for each device. This can, to some extend, be mitigated by creating a group for each contact you communicate with, and then add all their and your accounts to that group.
2. Message propagation is somewhat unreliable: If you use the method described in (1), some accounts may not receive a given message.
But yes, you needn't disclose your phone number in order to create an account/profile on SimpleX.