Rallies, fund raising, canvasing, community and work place organising, strikes, voting etc(And even then you need certain economic conditions to possible get a chance at real change). The only political use social media has during elections is when the Sanders campaign sent out warnings of incoming I.C.E raids or showing support to workers on strike, everything else it just screaming into the void.
Did any of the awful decisions Warren made during this campaign come as the result of people posting snake memes or are her decisions perfectly in line with someone who was a republican until the age of 40 and someone who took pride in gutting leftist education from her workplace. And the same with her supporters how many are actually not voting Bernie(And thus letting Biden win)due to the ''bro's'' online being mean rather than then looking for any old excuse not to possible one day pay for universal healthcare. feck even if they truly don't want to vote for Sanders because of the online memes, this only a expression of their own class interest, upper class white PMC viewing politics as a tv series where every four years they get to chose new characters. The kindest reading you could these Warren supporters is their stupid response over the online stuff is a reaction to a crisis of their ideology.
This is what the Sanders campaign is having to deal with.