There is an entire industry of shady companies who make tens of millions per by selling dogshit “secure comms” products to barely literate and computer illiterate LtCols and procurement officers in the US Government.
Those officers are close to retirement and by regurgitating big words they do not understand while still in their procurement positions, they can land a job at said company and receive some of those funds once they hit minimum retirement age and wait a year.
Signal is free and disruptive to those business models.
Ergo the misinformation campaign, the FUD, is well funded, by people who have a lot to lose.
13% is low, but I guess this shows how resistant to change people are. It’s better to establish a new market (or the first to become popular in a young market) than to try and come along with something disruptive in a mature market.