They have empathy for others and don't want to hurt anyone's feelings, vs Republicans don't care about others and take glee in hurting others feelings.
Or, they have the same masters as the Republicans and in order to actually stand against the Republicans on anything important they'd have to piss of their masters...
I feel like we need to look at the word resistance to get our answer: Resistance is about slowing something down, not stopping it and certainly not reversing it. So when Democrats are spineless, it’s because they aren’t actually ever trying to reverse what the Republicans are doing. Their job is to make sure whatever happens does so slower than the republicans might want it to. Both parties serve the same 100 people, but Democrats are trying to boil us slower. Apparently too slowly for those 100 people’s liking. And, because their job isn’t about helping people or reversing exploitation, they end up allowing a lot of horrifying change, only trying to make sure it happens more slowly or stealthily. If the frog finds out it’s being boiled, it might jump out before it can be cooked and served to the wealthy.