You make a good point. But the issue here is that, the leaders should be leading and not just talking about what leaders should do.

They always seem to get lost in their own noise.

Voices like Bernie, AOC, et al. will often start taking real action and garner positive national attention, but it regularly falls apart because the party as a whole seems uninterested in falling into line.

Nobody is supporting their good ideas because they keep waiting to get together on their perfect ideas, but spoiler that basically never happens. (They can be barely effective if they control the presidency and Congress, with Congress aligning to the president's agenda, but without that perfect environment they are effectively ineffective.)