Requiring Email Confirmation

I removed the requirement for having registered users confirm their emails from our onboarding. As a result of this and some other improvements, our onboarding finish-rate has gone from 60ish to 90ish percent.

We are a language learning website, and I noticed that our primary competitor (Duolingo) also doesn't block people from finishing onboarding until they confirm their email.

But I realized that there might be a hidden benefit to the email confirmation. Do email providers (especially Gmail) measure the open-rate of emails, and use it to decide which emails should go in the spam folder? In other words, will not requiring users to open at least one email from my site mean more emails we send are destined to spam folders?

I've seen other things mentioned in articles debating the pros and cons of requiring confirmation, but never this issue.