I suspect that the lessons learned then shaped the strategies used now for progressive candidates to win and probably even for which kind of progressive candidates were supported (it's my impression that this round of progressives are much more leftwing and much less centrist liberals that constantly blow identity-politics whistles whilst not talking about poverty and general inequality).

This round was even more reliant on grassroots support than previous rounds, for candidates who were against inequality in all its forms (including some openly calling themselves Socialist) and for electable positions that were a lot harder for the Democrat Party leadership to interfere in the choosing of (unlike with Bernie's Presidential primary, were even shit like super-representatives was in play to stop him).

Always has been

For context this is Bernie being arrested at a 1963 civil rights protest