Citation needed. Most of these, even if they include images, at least have a text version of the same content in the email because it's actually important for the sender that you can read them regardless of computing environment.

I use mutt, and AFAIK I've never missed anything due to it being in rendered into an image instead of included textually in the email. The images are useless static content, not real information rasterized on demand. Sometimes I do get HTML-only emails, but it's usually not hard to find the important stuff, if there is any, among the tags.

It’s not very hard to configure (neo)Mutt to display html only emails with w3m in the terminal. Makes it even easier to parse/read them

w3m will still fetch external assets, including tracking pixels. You have to use something like socksify to basically cut off network access for w3m.