This is completely untrue. Legal cases already have the concept of intent and liability. Section 230 provides blanket immunity for abuses that would otherwise be clearly defined as criminally negligent or willful behavior.

For example, without Section 230, one could define dang removing a harmful post shortly after it was flagged (usually within hours, I imagine) as best effort for a two-man moderation team, and find that PornHub, one of the most valuable web properties in the world with a significant amount of manpower, taking several weeks to take down a child porn video criminally negligent, and holding the company responsible. (Arguably, SESTA-FOSTA already enables the latter, as Section 230 no longer applies to sexual exploitation of children.)