Different people don’t like it for different reasons. Some people don’t like it because they think it has CIA financial backing (nope), and some people don’t like it because it requires your phone number, therefore it is not private (the privacy it provides is more than sufficient for anyone not actively being persecuted by a Five Eyes state), and some people don’t like it because it feels corporate (it’s a 501c3 nonprofit, and how corporate it feels is subjective).