CDA protects freedom of speech online by first protecting the intermediaries (e.g. Twitter) users rely on. By no means this encourages the hate speech, absusive language and all that, the misconducting individual may face civil lawsuits instead of the platform.
By the way Canada does not have Section 230 equivalent in place but tends to shadow our US neighbour when precedents / references are needed.
How easy can one build a civil or other cases on social media? It's easy when it comes to hate speech, terrorist propaganda, child pornagraph, racism but it is hard to build cases around defamation, including but not limited to libel and slander. Multiple facets account for such challenge but that's a different topic.