[DrScientist]

If I worked for the intelligence agencies I would be capturing all the info going in and out of the signal servers at the infrastructure level.

Even if I couldn't break the encryption I'd have timing and connectivity data.

So, if I were a user, I would always operate on the assumption that info would leak.

[Forbo]

In this threat model, the only defense you would have would be an overlay network resistant to correlation attacks where all nodes are involved in routing traffic (like I2P), or a mixnet like Katzenpost.

Getting people to use Tor for everything is hard enough, good luck getting people to use stuff even more obscure.