I run a data driven self help website and there is no paywall or advertising on the website. Everyone clearly signs up for emails. I still get above 0.5% spam+bounce ratio which means I need to ask Amazon for forgiveness everytime I email. (4x per year)
Yes I purge the lists, don't use clickbait, etc...
If 0.5% can get you into spam folders, this is an easy attack vector to silence someone.
My bigger question is how Walmart, Joann Fabrics, and HBO get into my mailbox. I'm sure they get "marked as spam" by more than 0.5%