Lack of accountability for the companies that allow their services & platforms to be used for spam/scamming.

Take DocuSign for instance. Still, this many years later, is a major source of phishing emails from their free trials. DocuSign could easily shut this down today by either requiring a CC for the trial, or forcing a call with a sales rep to start a trial. But they don't, they continue to allow their service to be used for wide scale phishing.

Atera, an RMM, is another one that has been a big source of malware delivery, also via the free trials.

Shutting down the trial accounts after the fact does nothing, the emails already went out.