If we're going to be fair, we have to acknowledge the history of email over the last thirty years: spam, spam filters, and the "Mark as Spam" button.

Email is what I use to notify my customers of a 25% sale, not to tell them that I'm going to plaster their data all over the internet in violation of the spirit of the service I'm providing. I use regular mail for that.

I’m not sure using snail mail as the default venue for important information is really the smart play here. I check my mailbox a lot less often then I check my inbox and I don’t even open 99% of the mail I get since I assume it’s just junk. I’m a lot more likely to miss whatever you sent me if you had sent it by post than if you had just sent an email like a normal 21st century organization.

I'm very much only addressing the small string of text I quoted; I agree it should have been opt-in since many people don't check their email diligently.

My problem with this is the automatic opt in, using my profile and details for more than I intended for them to use it for (regardless of whether I technically signed something staying they _could_ do this, it is borderline unethical to use my information for this purpose), only having a week to "opt out", and not knowing what opt out even does. Sending an email to everyone doesn't cure any of these points.

Not to mention that the only reference to needing to opt-out is a veiled mention buried in the second paragraph. I skimmed the email briefly, said “oh that’s neat, what a great idea” and filed it under “things for the next job hunt” thinking I’d turn on my profile then.

The link in the email did not work for me: it sent me to my profile, where I was presumably to be able to opt out of sharing my info publicly. But I could not see any way from there. Maybe I'm blind. As usual, googling worked better to find something on the site than using the site itself. Googled: triplebyte opt out -- that linked me to the right place. https://triplebyte.com/privacy-center

who reads those emails?

Precisely why this dark pattern is so common.