I agree that a lot of Saas startup are going to neglect security. But here we are talking about Knowledge base tools Saas companies. This is not some standard Saas company. They know they are in charge of company internal secrets. Or at lest I hope
I mean right this minute there's a privacy-focused SaaS on the front page for not being as private as everyone thinks. There's also a network hardware vendor on the front page for including back doors. A philosophy like "SaaS vendors know they can't allow security breaches" is really glossing over the need for layers of security and knowing that it's ultimately all on the trustworthiness of specifically who is involved.
I can't disagree with you. But you can either deny that the average Saas is more secure than a forgot Confluence internal servers exposed to the internet