Mail is the lingua franca of online communications. It isn't going anywhere any time soon, if only because it it's an independent standard that does not rely on some single commercial entity to continue operating it. That is also part of the reason why all those other services still fall back on email for their registration mechanisms.
And the Mediterranian Lingua Franca also faded away. I tend to agree with the person you're replying to, 95+% of my email is automated things sending it, it's rare that I have an email conversation with anybody these days. I don't like this trend, because I value open standards etc., hell I still use IRC regularly. But its use as a person-to-person communication mechanism is definitely falling, in my experience. Also, most mailing lists I'm on have been steadily drying up for a several years now.
I'm sure for some people that is the trend. For others, email is still doing just fine. Personally, I don't much like the kind of proprietary message board applications that trade off locking up your communications in someone else's system for using a prettier UI. Almost any individual online communication that I care about, whether personally or for business reasons, is done either via email or via some sort of self-hosted system that isn't trying to replace email. And speaking only for myself, I have had many email conversations catching up with old friends online while we can't meet in person because of the virus situation. YMMV, and presumably so will a few billion other people's. :-)
