Yeah it comes from the SPD betrayal (along with the most of II Internationale), SPD supported revolution in Germany only as far as it was bourgeoise revolution and didn’t even finished that, only as far as grabbing the power. But they sabotaged worker movement and cracked down violently on every attempt to fight, including at least 3 revolution attempts in 1919-1921, using police and far right freikorps formations. And they never opposed rightwingers like that, freikorps and nazis could organise without much opposition from the government, and during the Kapp putsch SPD did the ostrich and the workers had to save them for which SPD soon repaid with bullets in subsequent worker massacres.
Note that many workers were still members of SPD but their own party repaid them with repression for strikes and other struggle methods.
Yeah it comes from the SPD betrayal (along with the most of II Internationale), SPD supported revolution in Germany only as far as it was bourgeoise revolution and didn’t even finished that, only as far as grabbing the power. But they sabotaged worker movement and cracked down violently on every attempt to fight, including at least 3 revolution attempts in 1919-1921, using police and far right freikorps formations. And they never opposed rightwingers like that, freikorps and nazis could organise without much opposition from the government, and during the Kapp putsch SPD did the ostrich and the workers had to save them for which SPD soon repaid with bullets in subsequent worker massacres.
Note that many workers were still members of SPD but their own party repaid them with repression for strikes and other struggle methods.