We have our skills, and the ability to implement anything that we can imagine (with the necessary detail). They can't take that away.
Adoption remains a huge challenge (and not really one you solve with technology or skill). It doesn't help that design decisions that improve security can degrade the user experience, leading to lower adoption and lower security. Sigh.
I left it as "network effect". Probably too opaque.
It's like there was a window in the early 00s, when stuff like Tor, Freenet and I2P could recruit enough nodes to be viable. Remailer networks were just too damn hard to use. I mean, they were based on PGP plus mix networks.
But now, people expect stuff to be easy.
However, I2P is the only alternative that's been implemented at any scale, to my knowledge.
Papers have been published, yes. But I'm not aware of any other anonymity networks that have even gone public.
Why that is, I'm not sure. Maybe it's just network effect.